Customizable and programmable cell array

ABSTRACT

A logic array may include an array of programmable cells having a multiplicity of inputs and a multiplicity of outputs and customized interconnections providing permanent direct interconnections among at least a plurality of the multiplicity of inputs and at least a plurality of the multiplicity of outputs.

REFERENCE TO RELATED APPLICATIONS

This application is a continuation of assignee's application, U.S. Ser.No. 10/452,049, filed on Jun. 3, 2003 is now a U.S. Pat. 6,819,136,which is a continuation of assignee's application, U.S. Ser. No.09/803,373, filed on Mar. 12, 2001, now U.S. Pat. No. 6,756,811, whichis a continuation-in-part of assignee's pending application U.S. Ser.No. 09/659,783, filed on Sep. 11, 2000, now U.S. Pat. No. 6,331,790,which is a continuation-in-part of assignee's PCT InternationalApplication No. PCT/IL00/00149, all of which are incorporated byreference herein.

FIELD OF THE INVENTION

The present invention relates to integrated circuit devices as well asto methods for personalizing and programming such devices, methods forfinding faulty logic in integrated circuit devices and apparatus andtechniques for the design and manufacture of semiconductor devices.

BACKGROUND OF THE INVENTION

Various types of customizable integrated circuits and programmableintegrated circuits are known in the art. Customizable integratedcircuits include gate arrays, such as laser programmable gate arrays,commonly known as LPGA devices, which are described, inter alia in thefollowing U.S. Pat. Nos. 4,924,287; 4,960,729; 4,933,738; 5,111,273;5,260,597; 5,329,152; 5,565,758; 5,619,062; 5,679,967; 5,684,412;5,751,165; 5,818,728. Devices of this type are customized by etching orlaser ablation of metal portions thereof.

There are also known field programmable gate arrays, commonly known asFPGA devices, programmable logic devices, commonly known as PLD devices,as well as complex programmable logic devices, commonly known as CPLDdevices. Devices of these types are programmable by application ofelectrical signals thereto.

It has been appreciated in the prior art that due to the relatively highsilicon real estate requirements of FPGA devices, they are not suitablefor many high volume applications. It has therefore been proposed todesign functional equivalents to specific programmed FPGA circuits. Suchfunctional equivalents have been implemented in certain cases usingconventional gate arrays. The following U.S. Patents show suchimplementations: U.S. Pat. Nos. 5,068,063; 5,526,278 & 5,550,839.

Programmable logic devices are known in which programmable look uptables are employed to perform relatively elementary logic functions.Examples of such devices appear in U.S. Pat. Nos. 3,473,160 and4,706,216. Multiplexers are also known to be used as programmable logicelements. Examples of such devices appear in U.S. Pat. Nos. 4,910,417,5,341,041 and 5,781,033. U.S. Pat. Nos. 5,684,412, 5,751,165 and5,861,641 show the use of multiplexers to perform customizable logicfunctions.

Problems of clock skew in gate arrays are well known. U.S. Pat. No.5,420,544 describes a technique for reducing clock skew in gate arrayswhich employs a plurality of phase adjusting devices for adjusting thephase at various locations in gate arrays. Various clock tree designstructures have been proposed which produce relatively low clock skew.

PCT Published Patent Application WO 98/43353 describes a functionalblock architecture for a gate array.

U.S. Pat. No. 5,825,202 and U.S. Pat. No. 5,959,466 describes anintegrated semiconductor device comprising a FPGA portion connected to amask-defined application specific logic area.

Various types of gate arrays are well known in the art. Gate arrayscomprise a multiplicity of transistors, which are prefabricated. Aspecific application is achieved by customizing interconnections betweenthe transistors.

Routing arrangements have been proposed for reducing the number ofcustom masks and the time needed to manufacture gate arrays byprefabricating some of the interconnection layers in two-metal layergate array devices. Prior art devices of this type typically employthree custom masks, one each for the first metal layer, via layer andsecond metal layer.

U.S. Pat. No. 4,197,555 to Uehara describes a two-metal layer gate arraydevice wherein the first and second metal layers are pre-fabricated andthe via layer is customized. Uehara also shows use of pre-fabricatedfirst metal and via layers and customization of the second metal layer.

U.S. Pat. Nos. 4,933,738; 5,260,597 and 5,049,969 describe a gate arraywhich is customized by forming links in one or two prefabricated metallayers of a two-metal layer device.

U.S. Pat. No. 5,404,033 shows customization of a second metal layer of atwo-metal layer device.

U.S. Pat. No. 5,581,098 describes a gate array routing structure for atwo-metal layer device wherein only the via layer and the second metallayer are customized by the use of a mask.

Dual mode usage of Look-Up-Table SRAM cell to provide either a logicfunction or memory function has been proposed for FPGA devices in U.S.Pat. Nos. 5,801,547, 5,432,719 and 5,343,403.

Programmable and customizable logic arrays, such as gate arrays, arewell known and commercially available in various sizes and at variouslevels of complexity. Recently cores of such logic arrays have becomeavailable.

Conventionally, cores are provided by a vendor based on customer'sspecifications of gate capacity, numbers of input/output interfaces andaspect ratio. Each core is typically compiled by the vendor for theindividual customer order. Even though the cores employ modularcomponents, the compilation of the cores requires skilled technicalsupport and is a source of possible errors.

Examples of prior art proposals which are relevant to this technologyinclude Laser-programmable System Chips (LPSC), commercially availablefrom Lucent Technologies Inc., and Programmable Logic Device (PLD)cores, commercially available from Integrated Circuit Technology Corp.of California.

Integrated circuits are prone to errors. The errors may originate in thedesign of an integrated circuit in a logically incorrect manner, or fromfaulty implementation.

A debugging process is required to detect these errors but fault-findingis a difficult process in integrated circuit devices due to theinaccessibility of the individual gates and logic blocks within theintegrated circuit device.

The designer needs an apparatus and method for observing the behavior ofan integrated circuit device, while the device is in its “workingenvironment”. Furthermore, in order to isolate and determine a faultyarea or section of an integrated circuit device, a designer needs to beable to control the inputs to the faulty area or section(controllability), and also to be able to observe the output from thefaulty area (observability). In a typical integrated circuit device,controllability and observability are severely limited due to theinaccessibility of the device and the sequential nature of the logic.

The prior art teaches methods for enhancing the controllability and theobservability of an integrated circuit device. A method suggested byEichelberger et al., in “A Logic Design Structure for LSI Testability”,Proceeding of the 14^(th) Design Automation Conference, June 1977, is touse a “scan chain” method. In this method of Eichelberger, storageelements are tied together in one or more chains. Each of these chainsis tied to a primary integrated circuit pin. Special test clocks allowarbitrary data to be entered and scanned in the storage elementsindependent of the device's normal function.

The following US patents are believed to represent the current state ofthe art: U.S. Pat. Nos. 5,179,534; 5,157,627, and 5,495,486.

Semiconductor devices, such as ASICs, have traditionally beenmanufactured by ASIC design and fabrication houses having both ASICdesign and fabrication capabilities. Recently, however, the design andfabrication functionalities have become bifurcated, such that a customermay bring his fab-ready design to a fabrication house, having no designcapability. The customer may employ conventionally available celllibraries, such as those available, for example, from Artisan or MentorGraphics together with known design rules, to design their own devices.

Semiconductor design modules having specific functions, known as cores,are also available for integration by a customer into his design. Anexample of a commercially available core is a CPU core, commerciallyavailable from ARM Ltd. of Cambridge, England.

Cores may be provided in a variety of forms. For example, a “soft core”may be in the form of a high level schematic, termed RTL, while a “hardcore” may be at a layout level and be designed to specific fabricationdesign rules.

Conventional ASIC design flow is based on the use of synthesis softwarethat assists a design-engineer to convert the design from high-leveldescription code (RTL) to the level of gate netlist. Such a softwaretool is available from Synopsys Inc., 700 E. Middlefield, Mountain View,Calif., USA, and commercially available under the name of “DesignCompiler”. While software tools, such as “Design Compiler” are highlycomplex, they are limited by, for example, the number of logicfunctions, called “Library Functions”, which may be used for gate levelimplementation.

For example, “Design Compiler” can use up to about 1,000 logicfunctions. This relatively small number of logic functions limits theusefulness of “Design Compiler” with eCells. The term “eCell” is definedhereinbelow. A typical eCell may be configured to perform more than32,000 different logic functions.

Therefore there is a necessity in the art to provide a tool forsynthesizing an eCell.

SUMMARY OF THE INVENTION

The present invention seeks to provide an improved integrated circuitwhich, contrary to the teachings of the prior art, is both Customizableand programmable, and an improved integrated circuit which employs lookup tables to provide highly efficient logic cells and logicfunctionalities.

Additionally, the present invention seeks to provide a multiple layerinterconnection structure for a gate array device which has significantadvantages over prior art structures, and employs at least three metalinterconnection layers. customization is preferably realized bycustomization of a via layer and a layer overlying that via layer.Furthermore, the present invention seeks to provide a truly modularlogic array to be used as core and to be embedded in a system-on-chip(SoC), which is composed of a combination of identical modular logicarray units which are arranged in a desired mutual arrangement withoutthe requirement of compilation.

The following terms, which are used in the present specification andclaims, are defined as follows:

“eCell” is the building block of a configurable logic cell array.Typically, it is equivalent to about 15 ASIC logic gates.

“eUnit” is the structure of an array of 16×16 eCells with additionalcircuitry to support dual-port RAM mode XDEC and YDEC.

“RAW” is a structure of 16 eCells within an eUnit of cells, whichinclude a line-type structure that is parallel to the XDEC.

“CK-tree” or “Clock-tree” is a metal connecting structure that spreadsacross the logic to deliver the clock signal to the Flip/Flops (F/Fs)within that logic.

“½-eCore” is an array of 2×4 or 4×2 eUnits with additional circuits tosupport a clock driver, scan driver and counter with the logic tosupport loading the LUT's RAM for the set-up mode.

“eCore” is a structure comprising two ½-eCores to provide an array ofeither 4×4 eUnits or an array of 2×8 eUnits.

The present invention also seeks to provide an apparatus and method foradding controllability to fault-finding and debugging of an integratedcircuit device, and in particular to a Look-Up-Table (LUT) logic device,without any change to the rest of the circuit. LUT units are used inmany FPGA devices and also used in eASIC core devices, such as those ofeASIC of San Jose, Calif., USA, and described in U.S. patentapplications U.S. Ser. Nos. 09/265,998 and 09/310,962. Addingcontrollability to a RAM based LUT logic allows the debugging ofintegrated circuit devices within the working environment of the device.Although the present invention is described with respect to a 2-bit LUT,it is appreciated that the present method is also applicable to 3-bit,4-bit and even larger LUT devices.

Additionally, the present invention seeks to provide a method forautomatic distribution and licensing of semiconductor device cores,particularly “hard cores”, as well as a modifiable core particularlysuitable for use in the method. As the price of tooling andmanufacturing such S.O.C.'s is rapidly growing, and may be expected toexceed the $1 m mark for a 0.12 micron process, it is desirable to shareand spread the costs of tooling among several customers. Thus, inaccordance with yet another preferred embodiment of the presentinvention, the method for designing and manufacturing semiconductors mayalso involve an entity which provides the various services and resourcesrequired by a customer to design a required S.O.C. In the presentspecification and claims, the entity which provides this service istermed a “Virtual ASIC” entity.

An effective way for organizing this service is for the Virtual ASICentity to collect many different S.O.C. designs, which have beendeveloped by other companies and include a wide range of previouslybuilt-in options. Each entry into the library or data bank, includes theS.O.C. identification in addition to the identification of theindividual core included in it. The Virtual ASIC entity would then storeall the information in a data bank or library and make it available todifferent customers.

A customer wishing to design an S.O.C., chooses a device, from the databank, which is similar to his design requirements. The customerfinalizes his own S.O.C. design based on the device design and datastored in the library. A completed S.O.C. design bears the S.O.C.identification, in addition to the identification of the individual coreincluded in it. On completing the design of the S.O.C., the customer mayupdate the data bank held by the Virtual ASIC entity with his S.O.C.design and data.

As described hereinabove, these design S.O.C.'s may include dedicatedcomputerized functionalities, such as processors, DSP, and programmableand/or customizable logic.

Using various methods, adding mask tags, a Virtual ASIC entity maycalculate the costs for NRE and production which may result from thewafer costs, the royalty obligations due to the various bodies whichprovided the cores, and due to the S.O.C. integrator as well as theother service and customization charges.

Thus, the customer is now able to review the technical capabilities ofthe chip, the required NRE and the production costs of his design. Ifthe all the requirements of the customer are fulfilled, the customer canproceed and order the chip.

It is appreciated that such a service may be provided over the Internetto a customer who wishes to implement his own application based on thesimilar S.O.C. devices which are stored in the data bank of the VirtualASIC.

The customer may include his own software code for the processors and/orthe DSP and program and/or customize the logic to meet his ownparticular needs and requirements.

There is thus provided in accordance with a preferred embodiment of thepresent invention a personalizable and programmable integrated circuitdevice including at least first and second programmable logic cells andat least one permanent electrical conductive path interconnecting the atleast first and second programmable logic cells for personalization ofthe integrated circuit device, wherein the at least first and secondprogrammable logic cells are programmable by the application of anelectrical signal thereto.

Further in accordance with a preferred embodiment of the presentinvention the programmable logic cells include a programmable look-uptable.

Still further in accordance with a preferred embodiment of the presentinvention the a personalizable and programmable integrated circuitdevice includes at least first and second metal layers and a via layerto provide connection between the first metal layer and the second metallayer and wherein at least one of the first metal, second metal and vialayers includes a repeating pattern. Preferably, at least one of thefirst metal, second metal and via layers include a custom pattern.

There is provided in accordance with a preferred embodiment of thepresent invention an integrated circuit device including at least first,second and third metal layers and a first via layer to provideconnection between the first metal layer and the second metal layer anda second via layer to provide connection between the second metal layerand the third metal layer and wherein at least the first metal and thesecond metal layer include a repeating pattern and wherein at least oneof the first via, second via and third metal layers include a custompattern.

There is provided in accordance with another preferred embodiment of thepresent invention an integrated circuit device including at least first,second and third metal layers and a first via layer to provideconnection between the first metal layer and the second metal layer anda second via layer to provide connection between the second metal layerand the third metal layer and wherein at least the first metal and thethird metal layer include a repeating pattern and wherein at least oneof the first via, second via and third metal layers include a custompattern.

Further in accordance with a preferred embodiment of the presentinvention the device also includes a fourth metal layer.

Still further in accordance with a preferred embodiment of the presentinvention the fourth metal layer includes a repeating pattern.

Additionally in accordance with a preferred embodiment of the presentinvention the fourth metal layer includes a repeating pattern.

Preferably, the custom pattern is a via layer.

Further in accordance with a preferred embodiment of the presentinvention the custom pattern is prepared with direct write e-beamlithography.

Still further in accordance with a preferred embodiment of the presentinvention the first metal layer repeating pattern includes stripsextending generally in parallel to a first axis.

Further in accordance with a preferred embodiment of the presentinvention the third metal layer repeating pattern includes stripsextending generally in parallel to a first axis.

Still further in accordance with a preferred embodiment of the presentinvention at least two vias of first via layer are overlying at leastone of the strips connecting the strips to second metal layer.

Additionally in accordance with a preferred embodiment of the presentinvention the at least two vias are at a distance greater than 6 timesthan the distance between two adjacent the strips.

Further in accordance with a preferred embodiment of the presentinvention the strips are stepped strips and are in a band of generallyequal length strips.

Still further in accordance with a preferred embodiment of the presentinvention at least two vias are in propinquity to a beginning and an endof the at least one of the strips.

There is also provided in accordance with a preferred embodiment of thepresent invention the semiconductor device includes a substrate, atleast first, second and third metal layers are formed over thesubstrate, the second metal layer including a plurality of generallyparallel bands extending parallel to a first axis, each band including amultiplicity of second metal layer strips extending perpendicular to thefirst axis and at least one via connecting at least one second metallayer strip with the first metal layer underlying the second metallayer.

Further in accordance with a preferred embodiment of the presentinvention the third metal layer includes at least one third metal layerstrip extending generally perpendicular to the second metal layer stripsand being connected thereto by a via.

Still further in accordance with a preferred embodiment of the presentinvention the third metal layer includes at least one third metal layerstrip extending generally parallel to the second metal layer strips andconnecting two coaxial second metal layer strips by vias.

Preferably, the first metal layer includes at least one first metallayer strip extending generally perpendicular to the second metal layerstrips and is connected thereto by a via.

Additionally in accordance with a preferred embodiment of the presentinvention the semiconductor device also includes at least one thirdmetal layer strip extending parallel to the second metal layer strip andconnecting two coaxial second metal layer strips.

Further in accordance with a preferred embodiment of the presentinvention the via includes a repeating pattern of vias.

Further in accordance with a preferred embodiment of the presentinvention the semiconductor device further includes relatively shortsecond metal layer strips extending parallel to the first axis andlocated between the bands.

Still further in accordance with a preferred embodiment of the presentinvention the semiconductor device also includes at least one thirdmetal layer strip extending parallel to the second metal layer strip andconnecting two coaxial second metal layer strips.

Further in accordance with a preferred embodiment of the presentinvention the semiconductor device further includes a custom via layerconnecting at least one of the second metal layer strip to the thirdmetal layer.

Preferably, the third metal layer is a custom layer.

There is further provided in accordance with yet another preferredembodiment of the present invention a semiconductor device including asubstrate, at least first, second and third metal layers formed over thesubstrate, the first metal layer including a plurality of generallyparallel bands extending parallel to a first axis, each band including amultiplicity of first metal layer strips extending perpendicular to thefirst axis and at least one via connecting at least one third metallayer strip with the second metal layer underlying the third metallayer.

Further in accordance with a preferred embodiment of the presentinvention the second metal layer includes at least one second metallayer strip extending generally perpendicular to the first metal layerstrips and being connected thereto by a via.

Still further in accordance with a preferred embodiment of the presentinvention the second metal layer includes at least one second metallayer strip extending generally parallel to the first metal layer stripsand connecting two coaxial first metal layer strips by vias.

Additionally in accordance with a preferred embodiment of the presentinvention the third metal layer includes at least one third metal layerstrip extending generally parallel to the first metal layer strips andhaving conductive path thereto.

Further in accordance with a preferred embodiment of the presentinvention the semiconductor device also includes at least one secondmetal layer strip extending parallel to the first metal layer strip andconnecting two coaxial first metal layer strips.

Still further in accordance with a preferred embodiment of the presentinvention at least one via includes a repeating pattern of vias.

Additionally in accordance with a preferred embodiment of the presentinvention the semiconductor device further includes relatively shortfirst metal strips extending parallel to the first axis and locatedbetween the bands.

Preferably, the semiconductor device further includes at least onesecond metal layer strip extending parallel to the first metal layerstrip and connecting two coaxial first metal layer strips.

Further in accordance with a preferred embodiment of the presentinvention the semiconductor device also includes a custom via layerconnecting at least one of the first metal layer strip to the secondmetal layer.

Still further in accordance with a preferred embodiment of the presentinvention the second metal layer is a custom layer.

There is further provided in accordance with a preferred embodiment ofthe present invention a method for the design and the manufacture of asemiconductor device. The method includes producing a fab-ready designfor the semiconductor device by importing into the design at least onecore for a remote source the core bearing an identification indicium,utilizing the fab-ready design to fabricate the semiconductor device andreading the identification indicium to indicate the preparation of theat least one core therein.

Further in accordance with a preferred embodiment of the presentinvention the importing step includes communication of the core via acommunication link.

Still further in accordance with a preferred embodiment of the presentinvention the reading step is associated with a reporting step of thequantities of the core fabrication.

There is also provided in accordance with a preferred embodiment of thepresent invention a customizable and programmable integrated circuitdevice including at least first and second programmable logic cells, andat least two electrical conductive paths interconnecting the at leastfirst and second programmable logic cells, at least a portion of whichcan be removed for customization of the integrated circuit device,wherein the at least first and second programmable logic cells areprogrammable by the application of an electrical signal thereto.

Further in accordance with a preferred embodiment of the presentinvention, at least one of the at least two conductive paths defines ashort circuit between outputs of the at least first and secondprogrammable logic cells.

Still further in accordance with a preferred embodiment of the presentinvention the integrated circuit device is integrated into a largerdevice.

Additionally in accordance with a preferred embodiment of the presentinvention at least a majority of the at least one of the at least twoelectrical conductive paths interconnecting the at least first andsecond programmable logic cells constitutes repeated subpatterns.

There is presented in accordance with yet another preferred embodimentof the present invention, a method for customization and programming ofan integrated circuit device which includes providing an inoperativeintegrated circuit device, wherein the circuit device includes at leastfirst and second programmable logic cells, and at least two electricalconductive paths interconnecting the at least first and secondprogrammable logic cells, removing at least a portion of the at leasttwo electrical conductive paths for customization of the integratedcircuit devices, programming at least one of the at least first andsecond programmable logic cells by applying an electrical signalthereto, wherein the step of programming includes programming logicfunctions of the at least first and second programmable logic cells bythe application of an electrical signal thereto.

There is also provided in accordance with a further preferred embodimentof the present invention a logic cell for use in a logic array, thelogic cell includes at least one look-up table including a plurality ofLUT inputs and at least one output, and at least one logic gate having aplurality of logic inputs and an output coupled to one of the pluralityof LUT inputs.

Additionally in accordance with a preferred embodiment of the presentinvention a customizable and programmable integrated circuit devicewherein at least a majority of the at least one interconnection pathconstitutes repeated subpatterns.

Further in accordance with a preferred embodiment of the presentinvention the logic cell also includes a multiplexer connected to anoutput of at least one look-up table and an inverter selectablyconnectable to at least one of an output of the multiplexer and anoutput of the look-up table.

Still further in accordance with a preferred embodiment of the presentinvention the logic cell also includes a metal interconnection layeroverlying at least a portion of the cell for providing a custominterconnection between components thereof.

There is also provided in accordance with a preferred embodiment of thepresent invention a semiconductor device including a logic arrayincluding a multiplicity of identical logic cells, each identical logiccell comprising at least one look-up table, a metal connection layeroverlying the multiplicity of identical logic cells for providing apermanent customized interconnect between various inputs and outputsthereof.

Further in accordance with a preferred embodiment of the presentinvention the logic cell comprises at least one multiplexer and the atleast one look-up table provides an input to the at least onemultiplexer.

Still further in accordance with a preferred embodiment of the presentinvention, also including at least one logic gate connected to at leastone input of the look-up table. Preferably at least one multiplexer isconfigured to perform a logic operation on the outputs from the at leastone pair of look-up tables.

Additionally in accordance with a preferred embodiment of the presentinvention the look-up table is programmable.

Still further in accordance with a preferred embodiment of the presentinvention the logic cell includes at least one simple logic gateselectably connected to at least one logic cell output.

Moreover in accordance with a preferred embodiment of the presentinvention the logic array also includes a flip-flop for receiving anoutput from the multiplexer.

There is further provided in accordance with yet another preferredembodiment of the present invention a semiconductor device including alogic array comprising a multiplicity of identical logic cells, eachidentical logic cell including at least one flip-flop, and a metalconnection layer overlying the multiplicity of identical logic cells forinterconnecting various inputs and outputs thereof in a customizedmanner.

Further in accordance with a preferred embodiment of the presentinvention, the semiconductor device also includes a clock tree providingclock inputs to at least one of the at least one flip-flop of themultiplicity of identical logic cells.

Still further in accordance with a preferred embodiment of the presentinvention each logic cell receives a scan signal input which determineswhether the cell operates in a normal operation mode or a test operationmode, wherein in a test operation mode nearly each flip-flop receives aninput from an adjacent flip-flop thereby to define a scan chain.

Additionally in accordance with a preferred embodiment of the presentinvention the clock tree comprises a clock signal and an inverted clocksignal.

There is further provided in accordance with yet another preferredembodiment of the present invention a semiconductor device including asubstrate, at least first, second and third metal layers formed over thesubstrate, the second metal layer including a plurality of generallyparallel bands extending parallel to a first axis, each band comprisinga multiplicity of second metal layer strips extending perpendicular tothe first axis, and at least one via connecting at least one secondmetal layer strip with the first metal layer underlying the second metallayer.

Further in accordance with a preferred embodiment of the presentinvention the third metal layer includes at least one third metal layerstrip extending generally perpendicular to the second metal layer stripsand being connected thereto by a via. Alternatively, the third metallayer includes at least one third metal layer strip extending generallyparallel to the second metal layer strips and connecting two coaxialsecond metal layer strips by vias.

Still further in accordance with a preferred embodiment of the presentinvention the customizable logic core is customized for a specificapplication.

Additionally, the first metal layer comprises at least one first metallayer strip extending generally perpendicular to the second metal layerstrips and being connected thereto by a via. Preferably thesemiconductor device also includes at least one third metal layer stripextending parallel to the second metal layer strip and connecting twocoaxial second metal layer strips.

Still further in accordance with a preferred embodiment of asemiconductor device the at least one via includes a repeating patternof vias.

There is also provided in accordance with another preferred embodimentof the present invention a semiconductor device including a substrate,at least first, second, third and fourth metal layers formed over thesubstrate, the second metal layer comprising a plurality of generallyparallel bands extending parallel to a first axis, each band comprisinga multiplicity of long strips extending parallel to the first axis, thelong strips including at least one of straight strips and steppedstrips, at least one electrical connection between at least one strip inthe second metal layer to the third metal layer, which overlies thesecond metal layer, and wherein the second metal layer includes arepeating pattern.

Further in accordance with a preferred embodiment of the presentinvention the strips of the second metal layer are connected to one ofthe third metal layer and the fourth metal layer, both of which overliethe second metal layer, by at least two electrical connections.

Still further in accordance with a preferred embodiment of the presentinvention the semiconductor device forms part of a larger semiconductordevice.

Additionally in accordance with a preferred embodiment of the presentinvention the first metal layer comprises a plurality of generallyparallel bands extending parallel to a first axis, each band comprisinga multiplicity of long strips extending parallel to the first axis, thelong strips including at least one of straight strips and steppedstrips, at least one electrical connection between at least one strip inthe first metal layer to the third metal layer, which overlies the firstmetal layer. Preferably the first metal layer comprises a repeatingpattern.

There is provided in accordance with a preferred embodiment of thepresent invention an ASIC including at least one modular logic arraywhich is constructed of a plurality of modular logic array unitsphysically arranged with respect to each other to define a desiredaspect ratio.

Further in accordance with a preferred embodiment of the presentinvention each modular logic array unit includes a generallycircumferential border at which it is stitched onto any adjacent modularlogic array unit.

Still further in accordance with a preferred embodiment of the presentinvention each logic array unit comprises between 10,000 and 200,000gates.

Additionally in accordance with a preferred embodiment of the presentinvention each logic array unit has its own clock input.

There is further provided in accordance with a preferred embodiment ofthe present invention a data file for an ASIC which includes at least areference to a plurality of identical modular data files, eachcorresponding to a logic array unit and data determining the physicalarrangement of the logic units with respect to each other.

There is also provided in accordance with yet another preferredembodiment of the present invention a method for producing an ASICincluding the step of providing a plurality of modular logic array unitsphysically arranged with respect to each other to define a desiredaspect ratio.

Further in accordance with a preferred embodiment of the presentinvention each modular logic array unit includes a generallycircumferential border at which it is stitched onto any adjacent modularlogic array unit.

Still further in accordance with a preferred embodiment of the presentinvention each logic array unit comprises between 10,000 and 200,000gates.

There is also provided in accordance with another preferred embodimentof the present invention a method of producing a data file for an ASICwhich includes the following steps combining without compiling togethera plurality of identical modular data files, each corresponding to alogic array unit and data determining the physical arrangement of thelogic units with respect to each other.

Further in accordance with a preferred embodiment of the presentinvention each logic array unit comprises between 10,000 and 200,000gates.

Still further in accordance with a preferred embodiment of the presentinvention each logic array unit has its own clock input.

There is further provided in accordance with yet another preferredembodiment of the present invention a method of debugging an integratedcircuit comprising logic gates in the form of look up tables, whereineach logic table comprises at least two data bits, the method includesmodifying at least one of the data bits of one of the logic gates andexamining the effect of the modification on an output of the integratedcircuit without changing the routing. Preferably the modification ismade into a high level language data file. Additionally or alternativelythe high level language data file is used to modify a second data filecorresponding to the data bits of at least some of the logic gates.

Furthermore the modified second data file as applied to at least some ofthe logic gates to modify at least some of the data bits thereof.

There is provided in accordance with yet another preferred embodiment ofthe present invention a method for fault detection of an IntegratedCircuit (IC) including the steps of providing a first data file of ahigh level language with at least two signals defining a logic function,providing a second data file corresponding to the bit stream of aLook-Up-Table used to implement the logic function and modifying thesecond data file according to an user input signal to modify an outputsignal from the Look-Up-Table without changing the routing.

There is provided in accordance with another preferred embodiment of thepresent invention a method for design and manufacture of semiconductorsincluding the steps of producing a fab-ready design for a semiconductordevice by importing into the design at least one core from a remotesource, the core bearing an identification indicium, utilizing thefab-ready design to fabricate the semiconductor device, and reading theidentification indicium from the semiconductor device design to indicateincorporation of the at least one core therein.

Further in accordance with a preferred embodiment of the presentinvention the importing step includes communication of the core via theInternet.

Still further in accordance with a preferred embodiment of the presentinvention the reading step is associated with a reporting step whichpreferably includes reporting to an entity identified in the indiciumdata selected from the group consisting of the quantities of coresfabricated and the sizes the cores fabricated.

Preferably the producing step comprises interaction between a customerand a core provider's web site.

Additionally in accordance with a preferred embodiment of the presentinvention the plurality of the devices are stored as a library.Preferably the identification indicium of each of the plurality ofdevices includes an identification code of the ownership of the device.

Moreover in accordance with a preferred embodiment of the presentinvention the devices include a programmable and customizable logiccore.

There is also provided in accordance with a preferred embodiment of thepresent invention a semiconductor device including a plurality of pins,and customizable programmable logic containing a multiplicity of logiccells and a multiplicity of electrical connections between themultiplicity of logic cells, at least some of the multiplicity of logiccells being programmable by means of electrical signals supplied theretovia at least some of the plurality of pins, and at least some of themultiplicity of electrical connections being customized for a particularlogic function by lithography carried out in the course of manufactureof the semiconductor device.

There is also provided in accordance with a preferred embodiment of thepresent invention, a method of producing a semiconductor deviceincluding a plurality of pins and customizable programmable logiccontaining a multiplicity of logic cells and a multiplicity ofelectrical connections between the multiplicity of logic cells,including the steps of defining, on a semiconductor substrate, amultiplicity of logic cells which are programmable by means ofelectrical signals supplied thereto via at least some of the pluralityof pins, forming the multiplicity of electrical connections over thesemiconductor substrate by lithography, and in the course of the formingstep, customizing at least some of the multiplicity of electricalconnections for a specific logic function by lithography.

Further in accordance with a preferred embodiment of the presentinvention, the method also includes the step of programming at leastsome of the multiplicity of logic cells by means of electrical signalssupplied thereto via at least some of the plurality of pins.

There is further provided in accordance with yet another preferredembodiment of the present invention a method for recycling integratedcircuit designs including the steps of providing an integrated circuitdesign including multiple design elements from a design proprietor,removing at least part of the multiple design elements from theintegrated circuit design, supplying the integrated circuit designhaving removed therefrom the at least part of the multiple designelements to a design recipient, utilizing the integrated circuit designhaving removed therefrom the at least part of the multiple designelements by the design recipient to create a second integrated circuitdesign, providing compensation from the design recipient to the designproprietor for the use of the integrated circuit design having removedtherefrom the at least part of the multiple design elements.

There is also provided in accordance with another preferred embodimentof the present invention, a method for distributing integrated circuitdesigns including the steps of causing a proprietor of integratedcircuit designs to make them available to potential users for use andinspection, embedding in the integrated circuit designs identificationinformation when enables an integrated circuit fab to identify thesource of the designs in an integrated circuit fabricated on the basisthereof, causing the integrated circuit fab to identify the source ofthe integrated circuit designs using the identified information, andcausing the integrated circuit fab to pay compensation to the proprietorbased at least in part on identification of the integrated circuits.

There is provided in accordance with yet another preferred embodiment ofthe present invention an integrated circuit device including asemiconductor substrate defining a multiplicity of semiconductorelements, a plurality of metal layers formed over the semiconductorsubstrate by lithography, at least the semiconductor substrate beingdesigned such that the functionality of the multiplicity ofsemiconductor elements as being either logic or memory is determined bythe configuration of the plurality of metal layers.

Further in accordance with a preferred embodiment of the presentinvention the at least the semiconductor substrate is designed such thatthe functionality of the multiplicity of semiconductor elements as beingeither logic or memory is determined solely by the configuration of theplurality of metal layers.

There is also provided in accordance with yet another preferredembodiment of the present invention an integrated circuit deviceincluding a semiconductor substrate, and a plurality of metal layersformed over the semiconductor substrate and defining programmable logicincluding at least one ferroelectric element.

There is further provided in accordance with yet another preferredembodiment of the present invention an integrated circuit deviceincluding a semiconductor substrate, and a plurality of metal layersformed over the semiconductor substrate and being designed to enablerouting connections including at least three metal layers to becustomized by forming vias.

There is also provided in accordance with yet another preferredembodiment of the present invention a semiconductor device a pluralityof pins and customizable programmable logic containing a multiplicity oflogic cells and a multiplicity of electrical connections within themultiplicity of logic cells, at least some of the multiplicity of logiccells being programmable by means of electrical signals supplied theretovia at least some of the plurality of pins and by customization of theelectrical connections.

Further in accordance with a preferred embodiment of the presentinvention a semiconductor device, which also includes a multiplicity ofelectrical connections between the multiplicity of logic cells, at leastsome of the multiplicity of electrical connections being customized fora particular logic function by lithography carried out in the course ofmanufacture of the semiconductor device.

There is also provided in accordance with yet another preferredembodiment of the present invention a semiconductor device including aplurality of look up tables, each having a look up table output, amultiplexer having a plurality of inputs receiving the look up tableoutputs of the plurality of look up tables, and a switch arranged inseries between at least one of the look up table outputs and an input ofthe multiplexer, the switch enabling one of at least two of thefollowing inputs to be supplied to the input of the multiplexer: logiczero, logic 1, and the output of the look up table.

Further in accordance with a preferred embodiment of the presentinvention, the semiconductor device and also includes a flip flopreceiving an output of the multiplexer and wherein the switch enablesone of at least two of the following inputs to be supplied to the inputof the multiplexer: logic zero, logic 1, the output of the look up tableand the output of the flip flop.

There is further provided in accordance with yet another preferredembodiment of the present invention a method of employing synthesissoftware for integrated circuit design including the steps of definingfor the synthesis software a multiplicity of 2-input and 3-input logicfunctions, operating the synthesis software utilizing the multiplicityof 2-input and 3-input logic functions to provide a circuit design,mapping at least some of the logic functions for implementation by amultiplexer in a semiconductor device including a plurality of look uptables, each having a look up table output, a multiplexer having aplurality of inputs receiving the look up table outputs of the pluralityof look up tables, and a switch arranged in series between at least oneof the look up table outputs and an input of the multiplexer, the switchenabling one of at least two of the following inputs to be supplied tothe input of the multiplexer: logic zero, logic 1, and the output of thelook up table.

There is also provided in accordance with another preferred embodimentof the present invention a customizable and programmable integratedcircuit including at least first and second programmable logic cellseach having at least one input and at least one output, and at least onepermanent interconnection path interconnecting at least one output of atleast one of the first and second programmable logic cells with at leastone input of at least one of the first and second programmable logiccells.

Further in accordance with a preferred embodiment of the presentinvention the at least first and second programmable logic cells areprogrammable by the application of an electrical signal thereto.Preferably the logic functions of the at least first and secondprogrammable logic cells are programmable by the application of anelectrical signal thereto.

Still further in accordance with a preferred embodiment of the presentinvention the at least one interconnection path defines a short circuitbetween outputs of the at least first and second programmable logiccells.

Additionally in accordance with a preferred embodiment of the presentinvention the integrated circuit device comprises a stand-alone device.

Moreover in accordance with a preferred embodiment of the presentinvention the integrated circuit device is integrated into a largerdevice.

There is further provided in accordance with a preferred embodiment ofthe present invention a customizable logic array device including anarray of programmable cells having a multiplicity of inputs and amultiplicity of outputs, and customized interconnections permanentlyinterconnecting at least a plurality of the multiplicity of inputs andat least a plurality of the multiplicity of outputs.

There is also provided in accordance with a preferred embodiment of thepresent invention an array of field programmable gates having permanentcustomized connections.

Further in accordance with a preferred embodiment of the presentinvention the permanent customized connections are mask defined.

There is further provided in accordance with yet another preferredembodiment of the present invention a basic cell in a mask programmablegate array, the basic cell comprising at least one programmable logiccell.

Further in accordance with a preferred embodiment of the presentinvention the programmable logic cell comprises a Look-Up-Table.Preferably the Look-Up-Table comprises a mask programmable memory cell.

Still further in accordance with a preferred embodiment of the presentinvention the Look-Up-Table includes the following at least two inputs,and an electronic circuit which provides high speed response to changesin one of the two inputs with respect to the response time of changes tothe other input.

Additionally in accordance with a preferred embodiment of the presentinvention the Look-Up-Table is programmed at least twice during atesting process.

There is thus provided in accordance with a preferred embodiment of thepresent invention a customizable and programmable integrated circuitdevice including: at least first and second programmable logic cells,and at least two electrical conductive paths interconnecting the atleast first and second programmable logic cells, at least a portion ofwhich can be removed for customization of the integrated circuit device.

There is additionally provided in accordance with a preferred embodimentof the present invention a customizable and programmable integratedcircuit device including: at least first and second programmable logiccells, and at least one customizable electrical conductive pathinterconnecting the at least first and second programmable logic cells,the conductive path defining a short circuit between outputs of the atleast first and second programmable logic cells.

There is further provided in accordance with a preferred embodiment ofthe present invention a selectably configurable and field programmableintegrated circuit device including: at least first and second fieldprogrammable logic cells, and at least two electrical conductive pathsinterconnecting the at least first and second programmable logic cells,at least a portion of which can be removed for selectable configurationof the integrated circuit devices.

Preferably, the at least first and second programmable logic cells areprogrammable by the application of an electrical signal thereto.

In accordance with a preferred embodiment of the present invention,functions of the at least first and second programmable logic cells areprogrammable by the application of an electrical signal thereto andlogic functions of the at least first and second programmable logiccells are programmable by the application of an electrical signalthereto.

Preferably at least one of the at least two conductive paths defines ashort circuit between outputs of the at least first and secondprogrammable logic cells.

There is also provided in accordance with a preferred embodiment of thepresent invention a selectably configurable and programmable integratedcircuit device including: at least first and second programmable logiccells, and at least two selectably configurable electrical conductivepaths interconnecting the at least first and second programmable logiccells, at least one of which defines a short circuit between outputs ofthe at least first and second programmable logic cells.

Preferably, the at least first and second programmable logic cells areprogrammable by the application of an electrical signal thereto.

In accordance with a preferred embodiment of the present invention,functions, preferably comprising logic functions, of the at least firstand second programmable logic cells are programmable by the applicationof an electrical signal thereto.

Preferably, programming of the first and second programmable logic cellsmay take place following selectable configuration of the device.

There is additionally provided in accordance with a preferred embodimentof the present invention a selectably configurable and programmableintegrated circuit device wherein programming of the first and secondprogrammable logic cells may take place following selectableconfiguration of the device.

In accordance with a preferred embodiment of the present invention thefirst and second programmable logic cells may be reprogrammed.

There is also provided in accordance with a preferred embodiment of thepresent invention a method for customization and programming of anintegrated circuit device including: providing an inoperative integratedcircuit device including: at least first and second programmable logiccells, and at least one electrical conductive path interconnecting theat least first and second programmable logic cells, removing at least aportion of the electrical conductive path for customization of theintegrated circuit devices.

Preferably, the method also includes the step of programming at leastone of the at least first and second programmable logic cells byapplying an electrical signal thereto.

In accordance with a preferred embodiment of the present invention, thestep of programming includes programming functions, preferably includinglogic functions, of the at least first and second programmable logiccells by the application of an electrical signal thereto.

Preferably, the step of removing includes eliminating a short circuitbetween outputs of the at least first and second programmable logiccells by etching at least one conductive layer.

There is also provided in accordance with a preferred embodiment of thepresent invention a method for customization and programming of anintegrated circuit device including: providing an inoperative integratedcircuit device including at least first and second programmable logiccells, and at least two electrical conductive paths interconnecting theat least first and second programmable logic cells, removing at least aportion of the at least two electrical conductive paths for eliminatinga short circuit between outputs of the at least first and secondprogrammable logic cells.

There is additionally provided in accordance with a preferred embodimentof the present invention a method for selectable configuration andprogramming of an integrated circuit device including providing aninoperative integrated circuit device including at least first andsecond programmable logic cells, and at least two electrical conductivepaths interconnecting the at least first and second programmable logiccells, removing at least a portion of the at least two electricalconductive paths for selectable configuration of the integrated circuitdevice.

There is further provided a method for selectable configuration andprogramming of an integrated circuit device including providing aninoperative integrated circuit device including at least first andsecond programmable logic cells, and at least two electrical conductivepaths interconnecting the at least first and second programmable logiccells, and removing at least a portion of the at least two electricalconductive paths for eliminating a short circuit between outputs of theat least first and second programmable logic cells.

There is additionally provided in accordance with a preferred embodimentof the present invention a customizable and programmable integratedcircuit device including: at least first and second programmable logiccells which are programmable by application thereto of an electricalsignal, and at least two electrical conductive paths interconnecting theat least first and second programmable logic cells, at least a portionof which can be removed by etching for customization of the integratedcircuit device.

There is further provided in accordance with a preferred embodiment ofthe present invention a customized programmable integrated circuitdevice including at least first and second programmable logic cellswhich are programmable by application thereto of an electrical signal,and at least two electrical conductive paths interconnecting the atleast first and second programmable logic cells, at least a portion ofwhich has been removed by etching during customization of the integratedcircuit device.

It is appreciated that the integrated circuit device may comprise aconventional integrated circuit device having only a portion thereofconstructed and operative in accordance with the present invention to beboth customizable and programmable.

The present invention seeks to provide an improved integrated circuitwhich employs look up tables to provide highly efficient logic cells andlogic functionalities.

There is thus provided in accordance with a preferred embodiment of thepresent invention a logic cell for use in a logic array, the logic cellincluding: at least one look-up table including a plurality of LUTinputs and at least one output, and at least one logic gate having aplurality of logic inputs and an output coupled to one of the pluralityof LUT inputs.

According to one embodiment of the invention, the logic gate is a2-input logic gate. According to an alternative embodiment of theinvention, the logic gate is a NAND gate.

Preferably, the at least one look-up table includes at least one pair oflook-up tables.

In accordance with a preferred embodiment of the invention, the logiccell also includes a multiplexer receiving outputs from the at least onepair of look-up tables.

In accordance with another preferred embodiment of the invention, the atleast one look-up table includes first and second pairs of look-uptables, the logic cell also including first and second multiplexers,each multiplexer receiving outputs from a pair of look-up tables.

Preferably, the logic cell also includes a third multiplexer receivingoutputs from the first and second multiplexers.

Additionally in accordance with a preferred embodiment of the presentinvention, the logic cell also includes a flip-flop for receiving anoutput from the first multiplexer.

In accordance with an alternative embodiment of the present invention,the logic cell also includes a multiplexer connected to an output of atleast one look-up table and an inverter selectably connectable to atleast one of an output of the multiplexer and an output of the look-uptable.

The look-up table is preferably a programmable look-up table.

In accordance with a preferred embodiment of the present invention, thelogic cell also includes a metal interconnection layer overlying atleast a portion of the cell for providing a custom interconnectionbetween components thereof.

There is also provided in accordance with a preferred embodiment of thepresent invention a semiconductor device including a logic arrayincluding a multiplicity of identical logic cells, each identical logiccell including at least one look-up table, a metal connection layeroverlying the multiplicity of identical logic cells for providing apermanent customized interconnect between various inputs and outputsthereof.

Preferably each device includes at least one multiplexer and the atleast one look-up table provides an input to the at least onemultiplexer.

Additionally, each device preferably also includes at least one logicgate connected to at least one input of the look-up table.

According to one embodiment of the invention, the logic gate is a2-input logic gate. According to an alternative embodiment of theinvention, the logic gate is a NAND gate connected to an input of the atleast one look-up table.

Preferably, the at least one look-up table includes at least one pair oflook-up tables.

In accordance with a preferred embodiment of the present invention, theat least one multiplexer receives outputs from the at least one pair oflook-up tables. Preferably, the at least one multiplexer is configuredto perform a logic operation on the outputs from the at least one pairof look-up tables.

In accordance with an embodiment of the invention, the at least onelook-up table includes first and second pairs of look-up tables and theat least one multiplexer includes first and second multiplexers, eachmultiplexer receiving outputs from a pair of look-up tables.

Preferably, the look-up table is programmable.

In accordance with a preferred embodiment of the present invention, thedevice includes at least one simple logic gate selectably connected toat least one logic cell output.

Preferably, the simple logic gate is a two-input logic gate.Alternatively it may be an inverter or a buffer.

The device preferably also includes a multiplexer connected to an outputof at least one look-up table and an inverter selectably connectable toan output of the at least one multiplexer.

In accordance with a preferred embodiment of the present invention, thedevice also includes a metal interconnection layer overlying at least aportion of the cell for providing a custom interconnection betweencomponents thereof.

There is also provided in accordance with a preferred embodiment of thepresent invention a logic array including at least one logic cell, thelogic cell including: at least one look-up table including a pluralityof LUT inputs and at least one output, and at least one logic gatehaving a plurality of logic inputs and an output coupled to one of theplurality of LUT inputs.

The at least one look-up table is preferably a programmable look-uptable.

According to one embodiment of the invention, the logic array is a2-input logic gate. According to an alternative embodiment of theinvention, the logic gate is a NAND gate.

Preferably, the at least one look-up table includes at least one pair oflook-up tables.

In accordance with a preferred embodiment of the invention, the logicarray also includes a multiplexer receiving outputs from the at leastone pair of look-up tables.

In accordance with another preferred embodiment of the invention, the atleast one look-up table includes first and second pairs of look-uptables, the logic cell also including first and second multiplexers,each multiplexer receiving outputs from a pair of look-up tables.

Preferably, the logic array also includes a third multiplexer receivingoutputs from the first and second multiplexers.

Additionally in accordance with a preferred embodiment of the presentinvention, the logic array also includes a flip-flop for receiving anoutput from the first multiplexer.

In accordance with an alternative embodiment of the present invention,the logic array also includes a multiplexer connected to an output of atleast one look-up table and an inverter selectably connectable to atleast one of an output of the multiplexer and an output of the look-uptable.

In accordance with a preferred embodiment of the present invention, thelogic array also includes a metal interconnection layer overlying atleast a portion of the cell for providing a custom interconnectionbetween components thereof.

The logic array may be integrated into a larger device also formed onthe same substrate.

There is additionally provided in accordance with a preferred embodimentof the present invention a semiconductor device including a logic arrayincluding a multiplicity of identical logic cells, each identical logiccell including at least one flip-flop, and a metal connection layeroverlying the multiplicity of identical logic cells for interconnectingvarious inputs and outputs thereof in a customized manner.

The semiconductor device may also include a clock tree providing clockinputs to at least one of the at least one flip-flop of the multiplicityof identical logic cells.

Each logic cell in the semiconductor device may also receive a scansignal input which determines whether the cell operates in a normaloperation mode or a test operation mode, wherein in a test operationmode nearly each flip-flop receives an input from an adjacent flip-flopthereby to define a scan chain.

The logic cell preferably includes a programmable look-up table.

The present invention seeks to provide a multiple layer interconnectionstructure for a gate array device which has significant advantages overprior art structures.

The present invention employs at least three metal interconnectionlayers. Customization is preferably realized by customization of a vialayer and a layer overlying that via layer.

There is thus provided in accordance with a preferred embodiment of thepresent invention a semiconductor device including a substrate, at leastfirst, second and third metal layers formed over the substrate, thesecond metal layer including a plurality of generally parallel bandsextending parallel to a first axis, each band including a multiplicityof second metal layer strips extending perpendicular to the first axis,and at least one via connecting at least one second metal layer stripwith the first metal layer underlying the second metal layer.

Preferably the at least one via includes a repeating pattern of vias.

Further in accordance with a preferred embodiment of the presentinvention the third metal layer includes at least one third metal layerstrip extending generally perpendicular to the second metal layer stripsand being connected thereto by a via.

Still further in accordance with a preferred embodiment of the presentinvention the third metal layer includes at least one third metal layerstrip extending generally parallel to the second metal layer strips andconnecting two coaxial second metal layer strips by vias.

Additionally in accordance with a preferred embodiment of the presentinvention the first metal layer underlying the second metal layerincludes a multiplicity of first metal layer strips extending generallyparallel to the multiplicity of second metal layer strips. Furthermore,at least one of the first metal layer strips is electrically connectedat ends thereof to different second metal layer strips for providingelectrical connection therebetween.

Further in accordance with a preferred embodiment of the presentinvention the second metal layer strips include both relatively longstrips and relatively short strips, at least one of the relatively shortstrips being connected to the first metal layer by a via. Preferably therelatively short second metal layer strips are arranged in side by sidearrangement. Alternatively the relatively short second metal layerstrips are arranged in spaced coaxial arrangement.

Additionally or alternatively the third metal layer includes a bridgeconnecting adjacent pairs of the relatively short second metal layerstrips.

Still further in accordance with a preferred embodiment of the presentinvention the third metal layer includes at least one third metal layerstrip extending perpendicular to the second metal layer strips and beingconnected thereto by a via. Furthermore, the third metal layer includesat least one third metal layer strip extending parallel to the secondmetal layer strips and connecting two coaxial second metal layer stripsby vias.

Additionally in accordance with a preferred embodiment of the presentinvention the first metal layer comprises at least one first metal layerstrip extending generally perpendicular to the second metal layer stripsand being connected thereto by a via. Preferably the third metal layerincludes at least one third metal layer strip extending perpendicular tothe second metal layer strips and being connected thereto by a via.

Moreover in accordance with a preferred embodiment of the presentinvention the first metal layer includes first metal layer stripsextending generally perpendicular to the second metal layer strips, thefirst metal layer strips being electrically connected at ends thereof bythe vias to the second relatively short metal layer strips.

Still further in accordance with a preferred embodiment of the presentinvention the third metal layer comprises at least one third metal layerstrip extending parallel to the second metal layer strips and connectingtwo coaxial second metal layer strips by vias.

Additionally in accordance with a preferred embodiment of the presentinvention also including at least one third metal layer strip extendingparallel to the second metal layer strip and connecting two coaxialsecond metal layer strips.

There is also provided in accordance with a preferred embodiment of thepresent invention a semiconductor device including a substrate, at leastfirst, second and third metal layers formed over the substrate, thesecond metal layer including a multiplicity of second metal layer stripsextending perpendicular to the first axis, adjacent ones of the secondmetal layer strips having ends which do not lie in a single line.

Further in accordance with a preferred embodiment of the presentinvention the second metal layer strips are interlaced with one another.

Still further in accordance with a preferred embodiment of the presentinvention the third metal layer includes at least one third metal layerstrip extending generally perpendicular to the second metal layer stripand being connected thereto by a via.

Additionally in accordance with a preferred embodiment of the presentinvention the third metal layer includes at least one third metal layerstrip extending generally parallel to the second metal layer strips andconnecting two coaxial second metal layer strips by vias.

There is provided in accordance with yet another preferred embodiment ofthe present invention a semiconductor device including a substrate, atleast first, second and third metal layers formed over the substrate,the second metal layer including a plurality of generally parallel bandsextending parallel to a first axis, each band comprising a multiplicityof second metal layer strips extending perpendicular to the first axis,and a plurality of mutually parallel relatively short second metal layerstrips extending generally parallel to the first axis.

Further in accordance with a preferred embodiment of the presentinvention the third metal layer includes at least one third metal layerstrip extending generally perpendicular to the second metal layer stripsand being connected thereto by a via. Preferably at least one of thethird metal strips connects two second metal layer strips by means ofvias.

Still further in accordance with a preferred embodiment of the presentinvention the third metal layer includes at least one third metal layerstrip extending generally parallel to the second metal layer strips andconnecting two coaxial second metal layer strips by vias. Preferably atleast one of the third metal strips connects two second metal layerstrips by means of vias.

Additionally in accordance with a preferred embodiment of the presentinvention including at least one via connecting at least one secondmetal layer strip with the first metal layer underlying the second metallayer.

There is provided in accordance with yet another preferred embodiment ofthe present invention a semiconductor device including a substrate, atleast first, second, third and fourth metal layers formed over thesubstrate, the second metal layer including a plurality of generallyparallel bands extending parallel to a first axis, each band comprisinga multiplicity of long strips extending parallel to the first axis, thelong strips including at least one of straight strips and steppedstrips, at least one electrical connection between at least one strip inthe second metal layer to the third metal layer, which overlies thesecond metal layer.

Preferably the second metal layer comprises a repeating pattern.

Further in accordance with a preferred embodiment of the presentinvention the strips of the second metal layer are connected to one ofthe third metal layer and the fourth metal layer, both of which overliethe second metal layer, by least two electrical connections.

Alternatively most of the strips of the second metal layer are connectedto one of the third metal layer and the fourth metal layer, both ofwhich overlie the second metal layer, by least two electricalconnections.

Further in accordance with a preferred embodiment of the presentinvention at least one of the strips of the second metal layer iselectrically connected to another one of the strips of the second metallayer which is non-adjacent thereto.

Preferably the device forms part of a larger semiconductor device.

Still further in accordance with a preferred embodiment of the presentinvention the first metal layer includes a plurality of generallyparallel bands extending parallel to a first axis, each band comprisinga multiplicity of long strips extending parallel to the first axis, thelong strips including at least one of straight strips and steppedstrips, and at least one electrical connection between at least onestrip in the first metal layer to the third metal layer, which overliesthe first metal layer.

Additionally in accordance with a preferred embodiment of the presentinvention the first metal layer includes a repeating pattern.

Further in accordance with a preferred embodiment of the presentinvention the strips of the first metal layer are connected to one ofthe third metal layer and the fourth metal layer, both of which overliethe first metal layer, by least two electrical connections.

Alternatively most of the strips of the first metal layer are connectedto one of the third metal layer and the fourth metal layer, both ofwhich overlie the first metal layer, by least two electricalconnections.

Further in accordance with a preferred embodiment of the presentinvention at least one of the strips of the first metal layer iselectrically connected to another one of the strips of the first metallayer which is non-adjacent thereto.

Additionally in accordance with a preferred embodiment of the presentinvention the semiconductor device forms part of a larger semiconductordevice.

The present invention seeks to provide a truly modular logic array to beused as core and to be embedded in a system-on-chip, which is composedof a combination of identical modular logic array units which arearranged in a desired mutual arrangement without the requirement ofcompilation.

There is thus provided in accordance with a preferred embodiment of thepresent invention a modular logic array which is constructed of aplurality of modular logic array units physically arranged with respectto each other to define a desired aspect ratio.

There is also provided in accordance with a preferred embodiment of thepresent invention a data file for a modular logic array which comprisesat least a reference to a plurality of identical modular data files,each corresponding to a logic array unit and data determining thephysical arrangement of the logic units with respect to each other.

In accordance with one embodiment of the present invention, each modularlogic array unit includes a generally circumferential border at which itis stitched onto any adjacent modular logic array unit.

Preferably the stitching is effected by removable conductive stripsformed in a relatively high metal layer which are connected by vias tostrips in a relatively lower metal layer, thereby to removably bridgegaps therebetween.

There is also provided in accordance with a preferred embodiment of thepresent invention an application specific integrated circuit (ASIC)including at least one modular logic array which is constructed of aplurality of modular logic array units physically arranged with respectto each other to define a desired aspect ratio.

Further in accordance with a preferred embodiment of the presentinvention each modular logic array unit includes a generallycircumferential border at which it is stitched onto any adjacent modularlogic array unit.

Still further in accordance with a preferred embodiment of the presentinvention adjacent modular logic array units display stitching at acommon border thereof, the stitching being effected by removableconductive strips formed in a relatively high metal layer which areconnected by vias to strips in a relatively lower metal layer, therebyto removably bridge gaps therebetween.

Additionally in accordance with a preferred embodiment of the presentinvention at least two adjacent modular logic array units are arrangedto have their scan inputs and scan outputs in parallel. Alternatively oradditionally at least two adjacent modular logic array units arearranged to have their scan inputs and scan outputs in series.

Moreover in accordance with a preferred embodiment of the presentinvention, the ASIC includes modular logic array units of at least twodifferent geometrical configurations.

Preferably, each logic array unit includes between 10,000 and 200,000gates.

Further in accordance with a preferred embodiment of the presentinvention each logic array unit has an area of between 0.5 squaremillimeter and 6 square millimeters.

Additionally in accordance with a preferred embodiment of the presentinvention each logic array unit has its own clock input and clockoutput. Furthermore each logic array unit has its own scan input andscan output.

There is also provided in accordance with yet another preferredembodiment of the present invention, a data file for an ASIC whichincludes at least a reference to a plurality of identical modular datafiles, each corresponding to a logic array unit and data determining thephysical arrangement of the logic units with respect to each other.

Further in accordance with a preferred embodiment of the presentinvention each modular logic array unit includes a generallycircumferential border at which it is stitched onto any adjacent modularlogic array unit.

Still further in accordance with a preferred embodiment of the presentinvention adjacent modular logic array units display stitching at acommon border thereof, the stitching being effected by removableconductive strips formed in a relatively high metal layer which areconnected by vias to strips in a relatively lower metal layer, therebyto removably bridge gaps therebetween.

Additionally in accordance with a preferred embodiment of presentinvention at least two adjacent modular logic array units are arrangedto have their scan inputs and scan outputs in parallel. Alternatively oradditionally at least two adjacent modular logic array units arearranged to have their scan inputs and scan outputs in series.

Further in accordance with a preferred embodiment of the presentinvention, a data file which includes modular logic array units of atleast two different geometrical configurations. Preferably each logicarray unit comprises between 10,000 and 200,000 gates.

Moreover in accordance with a preferred embodiment of the presentinvention each logic array unit has an area of between 0.5 squaremillimeter and 6 square millimeters.

Still further in accordance with a preferred embodiment of the presentinvention each logic array unit has its own clock input and clockoutput.

Additionally each logic array unit has its own scan input and scanoutput.

There is also provided in accordance with yet another preferredembodiment of the present invention, a method for producing an ASICincluding the steps of providing a plurality of modular logic arrayunits physically arranged with respect to each other to define a desiredaspect ratio.

Further in accordance with a preferred embodiment of the presentinvention each modular logic array unit includes a generallycircumferential border at which it is stitched onto any adjacent modularlogic array unit.

Still further in accordance with a preferred embodiment the presentinvention wherein adjacent modular logic array units are stitched at acommon border thereof, stitching being effected by removable conductivestrips formed in a relatively high metal layer which are connected byvias to strips in a relatively lower metal layer, thereby to removablybridge gaps therebetween.

Additionally in accordance with a preferred embodiment of the presentinvention at least two adjacent modular logic array units are arrangedto have their scan inputs and scan outputs in parallel.

Furthermore at least two adjacent modular logic array units are arrangedto have their scan inputs and scan outputs in series.

Moreover in accordance with a preferred embodiment of the presentinvention and including modular logic array units of at least twodifferent geometrical configurations.

Still further in accordance with a preferred embodiment of the presentinvention each logic array unit comprises between 10,000 and 200,000gates. Furthermore each logic array unit has an area of between 0.5square millimeter and 2 square millimeters.

Further in accordance with a preferred embodiment of the presentinvention each logic array unit has its own clock input and clockoutput. Additionally each logic array unit has its own scan input andscan output.

There is provided in accordance with another preferred embodiment of thepresent invention a method of producing a data file for an ASIC whichincludes combining without compiling together a plurality of identicalmodular data files, each corresponding to a logic array unit and datadetermining the physical arrangement of the logic units with respect toeach other.

Further in accordance with a preferred embodiment of the presentinvention each modular logic array unit includes a generallycircumferential border at which it is stitched onto any adjacent modularlogic array unit.

Still further in accordance with a preferred embodiment of the presentinvention a method of adjacent modular logic array units displaystitching at a common border thereof, the stitching being effected byremovable conductive strips formed in a relatively high metal layerwhich are connected by vias to strips in a relatively lower metal layer,thereby to removably bridge gaps therebetween.

Additionally in accordance with a preferred embodiment the presentinvention at least two adjacent modular logic array units are arrangedto have their scan inputs and scan outputs in parallel. Furthermore atleast two adjacent modular logic array units are arranged to have theirscan inputs and scan outputs in series.

Moreover in accordance with a preferred embodiment of the presentinvention including modular logic array units of at least two differentgeometrical configurations.

Preferably each logic array unit comprises between 10,000 and 200,000gates.

Additionally in accordance with a preferred embodiment of the presentinvention each logic array unit has an area of between 0.5 squaremillimeter and 6 square millimeters.

Still further in accordance with a preferred embodiment of the presentinvention each logic array unit has its own clock input and clockoutput. Additionally each logic array unit has its own scan input andscan output.

There is thus provided in accordance with a preferred embodiment of theinvention a method of testing an integrated circuit comprising logicgates in the form of look up tables, wherein each logic table comprisesat least two data bits, the method comprising modifying at least one ofthe data bits of one of the logic gates, and examining the effect of themodification on an output of the integrated circuit.

Further in accordance with a preferred embodiment of the presentinvention the logic gates are formed into groups within the integratedcircuit, each group having at least two inputs and at least one output.Preferably the logic gates do not have independent inputs or independentoutputs.

Additionally in accordance with a preferred embodiment of the presentinvention the modification is made into a high level language data file.Preferably the high level language data file is used to modify a seconddata file corresponding to the data bits of at least some of the logicgates. Additionally or alternatively the modified second data file asapplied to at least some of the logic gates to modify at least some ofthe data bits thereof.

Moreover in accordance with a preferred embodiment of the presentinvention the step of selecting a modification of a given logic gatewithin a group to have the effect of neutralizing the effect of thegiven logic gate on an output of the group. Preferably the group isarranged as a flip-flop.

The present invention seeks to provide a method for automaticdistribution and licensing of semiconductor device cores, particularly“hard cores” as well as a modifiable core particularly suitable for usein the method.

There is thus provided in accordance with a preferred embodiment of thepresent invention a method for design and manufacture of semiconductorsincluding producing a fab-ready design for a semiconductor device byimporting into the design at least one core from a remote source, thecore bearing an identification indicium, utilizing the fab-ready designto fabricate the semiconductor device and reading the identificationindicium from the semiconductor device to indicate incorporation of theat least one core therein.

In accordance with a preferred embodiment of the present invention,there is provided a programmable or customizable core structure whichcan be incorporated in a design for a semiconductor device and whichenables a user to assemble therewithin both conventional cores andprogrammable and customizable elements associatable therewith.

In accordance with a preferred embodiment of the present invention, theimporting step includes communication of the core via a communicationslink, preferably the Internet.

Preferably, the reading step is associated with a reporting step whichpreferably includes reporting to an entity identified in the indiciumthe quantities and/or sizes of cores fabricated. This reporting step ispreferably carried out by the fabrication facilities, preferably thefoundry or mask shop as defined hereinbelow.

As the price of tooling and manufacturing such S.O.C's is rapidlygrowing, and may be expected to exceed the $1m mark for a 0.12 micronprocess, it is desirable to share and spread the costs of toolingamongst several customers.

Thus, in accordance with yet another preferred embodiment of the presentinvention, the method for designing and manufacturing semiconductors mayalso include the use of a company or body which provides the variousservices and resources required by a customer to design a requiredsystem on a chip.

In the present specification and claims, the company which provides thisservice is known as a “Virtual ASIC” company.

An effective way for organizing this service is for the Virtual ASICcompany to collate many different S.O.C. designs, which have beendeveloped by other companies and include a wide range of previouslybuilt-in options. Each entry into the library or data bank, includes theS.O.C. identification in addition to the identification of theindividual core included in it. The Virtual ASIC company would thenstore all the information in a data bank or library and make itavailable to different customers.

A customer wishing to design an S.O.C., chooses a device, from the databank, which is similar to his design requirements. The customerfinalizes his own S.O.C. design based on the device design and datastored in the library. A completed S.O.C. design bears the S.O.C.identification, in addition to the identification of the individual coreincluded in it. On completing the design of the S.O.C., the customer mayupdate the data bank held by the Virtual ASIC company with his S.O.C.design and data.

As described by the previous embodiments of the present invention, thesedesign S.O.C.'s may include dedicated computerized functions, such asprocessors, DSP, and programmable and/or customizable logic.

Using different methods, such as known in the art computer codes, theVirtual ASIC company may calculate the costs for NRE and productionwhich may result from the wafer costs, the royalty obligations to thevarious bodies which provided the cores, and to the S.O.C. integratorand the other service and customization charges.

Thus, the customer is now able to review the technical capabilities ofthe chip, the required NRE and the production costs of his design. Ifthe all the requirements of the customer are fulfilled, the customer nowgo ahead and order the chip.

It is appreciated that such a service may be provided over the Internetto a customer who is interested to implement his own application basedon the similar S.O.C. devices which are stored in the data bank of theVirtual ASIC.

The customer may include his own software code for the processors and/orthe DSP and to program and/or customize the logic to meet the customer'sown particular needs and requirements.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be understood and appreciated more fully fromthe following detailed description, taken in conjunction with thedrawings in which:

FIGS. 1A and 1B show a simplified illustration of a customizable andprogrammable integrated circuit device constructed and operative inaccordance with a preferred embodiment of the present invention;

FIG. 2 is a more detailed illustration of a portion of the integratedcircuit device of FIG. 1 including both customizable and programmableportions;

FIG. 3 is an illustration of the circuitry of FIG. 2 followingcustomization for one type of functionality;

FIG. 4 is an illustration of the circuitry of FIG. 2 followingcustomization for another type of functionality;

FIG. 5 is an equivalent circuit illustrating the circuitry of FIG. 3following customization and programming for one type of functionality;

FIG. 6 is an equivalent circuit illustrating the circuitry of FIG. 3following customization and programming for another type offunctionality;

FIG. 7 is an equivalent circuit illustrating the circuitry of FIG. 4following customization and programming for one type of functionality;

FIG. 8 is an equivalent circuit illustrating the circuitry of FIG. 4following customization and programming for another type offunctionality;

FIG. 9 is a Look Up Table illustrating part of the functionality of thecircuitry of FIGS. 2–4;

FIG. 10 is a simplified illustration of the gate layer of a logic cellconstructed and operative in accordance with one preferred embodiment ofthe present invention;

FIG. 11 is a simplified illustration of the gate layer of a logic cellconstructed and operative in accordance with another preferredembodiment of the present invention;

FIG. 12 is a simplified illustration of a gate layer of a plurality oflogic cells which constitute a portion of a logic array in accordancewith a preferred embodiment of the present invention;

FIG. 13 is a simplified illustration of a gate layer of a plurality oflogic cells which constitute a portion of a logic array and incorporatea clock tree in accordance with a preferred embodiment of the presentinvention; and

FIG. 14 is a simplified illustration of a gate layer of a plurality oflogic cells which constitute a portion of a logic array and incorporatea scan chain in accordance with a preferred embodiment of the presentinvention.

FIG. 15 is a pictorial illustration of the lower two of the top threemetal layers of a cell array device constructed and operative inaccordance with a preferred embodiment of the present invention, priorto customization;

FIG. 16 is a pictorial illustration corresponding to FIG. 15 followingcustomization thereof in accordance with a preferred embodiment of thepresent invention;

FIG. 17 is a schematic illustration corresponding to FIG. 15;

FIG. 18 is a schematic illustration corresponding to FIG. 16;

FIG. 19 is a schematic illustration corresponding to FIGS. 15 & 17 butshowing a variation in the arrangement of the lowest of the three metallayers;

FIG. 20 is a schematic illustration corresponding to FIG. 19 followingcustomization thereof in accordance with a preferred embodiment of thepresent invention;

FIG. 21 is a schematic illustration corresponding to FIGS. 15 & 17 butshowing a variation in the arrangement of the middle of the three metallayers;

FIG. 22 is a schematic illustration corresponding to FIG. 21 followingcustomization thereof in accordance with a preferred embodiment of thepresent invention;

FIGS. 23A and 23B schematically illustrate the lower four of the topfive metal layers of a cell array device constructed and operative inaccordance with another preferred embodiment of the present invention,prior to customization;

FIGS. 24A and 24B show a schematic illustration corresponding to FIGS.23A and 23B following customization thereof in accordance with apreferred embodiment of the present invention;

FIGS. 25A, 25B, and 25C schematically illustrate the lower four of thetop five metal layers of a cell array device constructed and operativein accordance with yet another preferred embodiment of the presentinvention, prior to customization;

FIGS. 26A, 26B, and 26C show a schematic illustration corresponding toFIGS. 25A, 25B, and 25C following customization thereof in accordancewith a preferred embodiment of the present invention;

FIG. 27 is a schematic illustration corresponding to FIG. 15 withadditional bridges in the middle of the top three metal layers;

FIG. 28 is a schematic illustration corresponding to FIG. 27 and showingthe top metal layer, prior to customization;

FIG. 29 is a schematic illustration corresponding to FIG. 28 having viacustomization in accordance with a preferred embodiment of the presentinvention;

FIG. 30 illustrates a single routing cell unit, comprising layers M4 toM6 and I/O contacts in accordance with a preferred embodiment of thepresent invention;

FIG. 31 illustrates a single routing cell unit of similar constructionto the single cell routing unit of FIG. 30, but without the I/Ocontacts;

FIG. 32 illustrates typical routing connections in the M3 and M4 layers,and the M3M4 via and M4M5 via layers, of the single routing cell unit,in accordance with a preferred embodiment of the present invention;

FIG. 33 illustrates an M5 layer corresponding to the arrangementdescribed hereinabove with respect to FIG. 19;

FIG. 34 illustrates an M6 layer with vias M5M6 corresponding to the M6layers of FIG. 23;

FIG. 35 illustrates a typical arrangement of 16 cells of M3 and M4layers in a 4×4 matrix, in accordance with a preferred embodiment of thepresent invention;

FIG. 36 illustrates an M5 layer comprising a 4×4 matrix of 16 cells, inaccordance with a preferred embodiment of the present invention;

FIG. 37 illustrates an M6 layer and M5M6 via layer of a 4×4 cell matrix,in accordance with a preferred embodiment of the present invention;

FIG. 38 illustrates the layers M3, M4, M5, M6 and M7 in a 4×4 cellmatrix, in accordance with a preferred embodiment of the presentinvention;

FIG. 39 illustrates a cell preferably forming part of a gate layer of acell array device constructed and operative in accordance with yetanother preferred embodiment of the present invention;

FIG. 40 shows routing cell overlaying cell 3200 including jumperconnections for providing programmable connections between thecomponents of the cell 3200 of FIG. 39;

FIG. 41 presents a detailed configuration of a LUT-3 device, constructedand operative in accordance with a preferred embodiment of the presentinvention;

FIG. 42 is a schematic drawing of a single RAM cell 3110A of FIG. 41;

FIG. 43 is a typical layout of a single cell 3200 of FIG. 39;

FIG. 44 shows the layout of Metal 2, Metal 3, and Metal 4 of the cell3200, of FIG. 39, which is overlaying the layout of FIG. 43, inaccordance with the preferred embodiment of the present invention;

FIG. 45A presents a layout of an eUnit, comprising an array of 16×16cells 3200, in accordance with the preferred embodiment of the presentinvention;

FIG. 45B shows a layout of a ½-eCore unit, in accordance with thepreferred embodiment of the present invention;

FIG. 46 illustrates a repeating circuit within the XDEC circuit forcontrolling the Word Lines WL, in accordance with the preferredembodiment of the present invention;

FIG. 47 illustrates a repeating circuit within YDEC circuit forproviding the necessary control to the bit lines BL, BLB, in accordancewith the preferred embodiment of the present invention;

FIG. 48 shows the logic of the control line of FIG. 47, in accordancewith the preferred embodiment of the present invention;

FIG. 49 illustrates eight eUnits arranged in a 2×4 array, constructedand operative in accordance with another preferred embodiment of thepresent invention;

FIG. 50 shows a typical clock unit located within the eUnit, constructedand operative in accordance with another preferred embodiment of thepresent invention;

FIG. 51 presents a circuit for providing reduced power and supply noisereduction, constructed and operative in accordance with anotherpreferred embodiment of the present invention;

FIG. 52 illustrates the new charge of the CK and CKB drivers inaccordance with another preferred embodiment of the present invention;

FIG. 53 presents a typical circuit useful for generating the timing linesignal for turning-on and turning-off the transistor 3792 of FIG. 51, inaccordance with a preferred embodiment of the present invention;

FIG. 54 is a flowchart illustrating a method for using the code “DesignCompiler” for programming the cell 3200 of FIG. 39 to perform more than32,000 different logic functions, in accordance with a preferredembodiment of the present invention;

FIG. 55 presents the typical steps useful in implementing step 3905 inthe flowchart of FIG. 54;

FIG. 56A is a schematic diagram of a “fixed connection” device, inaccordance with another preferred embodiment of the present invention;

FIG. 56B is a schematic diagram of a “fixed connection” device for lowlevel logic, in accordance with a preferred embodiment of the presentinvention;

FIG. 56C is a schematic diagram of a “fixed connection” device for highlevel logic, in accordance with a preferred embodiment of the presentinvention;

FIGS. 57A and 57B show a simplified illustration of a typical system onchip device comprising a plurality of identical logic array modules inaccordance with a preferred embodiment of the present invention;

FIGS. 58A, 58B and 58C are simplified illustrations of three differentembodiments of logic array modules useful in the present invention;

FIGS. 59A and 59B are simplified illustrations of two differentarrangements of identical logic array modules useful in accordance withthe present invention; and

FIGS. 60A and 60B are simplified illustrations of logic array modulestiled together in two different arrangements.

FIG. 61 is a simplified illustration of a programmable IntegratedCircuit (IC) device constructed and operative according to a preferredembodiment of the present invention;

FIG. 62A is a shows a simplified representation of the layout of theconnecting pins of a simplified of a LUT device constructed andoperative according to a preferred embodiment of the present invention;

FIG. 62B shows the truth table of a typical LUT-2 device;

FIGS. 62C and 62D show the truth tables of a LUT device before and afterreprogramming, in accordance with a preferred embodiment of the presentinvention;

FIG. 63A illustrates the typical connections of a logic gate device;

FIG. 63B is a schematic drawing of the device shown of FIG. 63A;

FIG. 63C is the truth table of the device shown in FIGS. 63A and 63B;

FIG. 64A shows the truth tables of the LUT units of the device of FIG.63A after LUT device 34 is forced to “0”;

FIG. 64B is a schematic drawing of the device whose truth table is shownin FIG. 64A;

FIG. 65A shows the truth table of a LUT device of FIG. 64A after the LUTdevice 34 is forced to “1”;

FIG. 65B is a schematic drawing of the device whose truth table is shownin FIG. 65A;

FIG. 66A presents the truth tables for the device after LUT 34 is forcedto a first complementary function;

FIG. 66B is a schematic drawing of the LUT unit of FIG. 66A;

FIG. 67A presents the truth tables for the device after LUT 34 is forcedto a second complementary function;

FIG. 67B is a schematic drawing of the LUT unit of FIG. 67A.

FIG. 68 is a simplified flowchart illustrating a preferred method ofsemiconductor design and fabrication in accordance with a preferredembodiment of the present invention;

FIGS. 69A and 69B are together a flowchart illustrating a preferredmethod of semiconductor design and fabrication in accordance with apreferred embodiment of the present invention;

FIG. 70 is a simplified flowchart illustrating the method in which aVirtual ASIC entity interacts with a customer to provide cost effectivechip production; and

FIG. 71A is a schematic illustration of the top four metal layers of acell array device constructed and operative in accordance with anotherpreferred embodiment of the present invention, prior to customization;

FIG. 71B shows in more detail the periodic connections of FIG. 71A;

FIG. 72 is a schematic illustration corresponding to FIG. 71A followingcustomization thereof in accordance with the present invention;

FIG. 73 illustrates a single routing cell unit, comprising M4 and M5layers and a M4M5 via, in accordance with the preferred embodiment ofthe present invention;

FIG. 74 illustrates a single routing cell unit, comprising M5 and M6layers, in accordance with the preferred embodiment of the presentinvention;

FIG. 75 illustrates a single routing cell unit, comprising M6 and M7layers and a M6M7 via, in accordance with the preferred embodiment ofthe present invention;

FIG. 76 illustrates a unit, comprising M4 and M5 layers and a M4M5 viaof a 2×2 cell matrix, in accordance with a preferred embodiment of thepresent invention;

FIG. 77 illustrates a unit, comprising M5 and M6 layers of a 2×2 cellmatrix, in accordance with a preferred embodiment of the presentinvention; and

FIG. 78 illustrates a unit, comprising M6 and M7 layers and a M6M7 viaof a 2×2 cell matrix, in accordance with a preferred embodiment of thepresent invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Reference is now made to FIGS. 1A and 1B, which together show asimplified illustration of a customizable and programmable integratedcircuit device constructed and operative in accordance with a preferredembodiment of the present invention. The integrated circuit device ofFIGS. 1A and 1B may be a stand-alone device or may alternatively beintegrated into a larger device. In the latter case, the device mayconstitute a customizable and programmable portion of a system on achip. The present invention relates to both of the aboveimplementations, notwithstanding that the following description, for thesake of simplicity and conciseness, describes only the stand-alonedevice.

FIGS. 1A and 1B illustrate a device typically including four metallayers, designated by reference numerals 20, 22, 24 and 26.

Preferably, the top metal layer 26 is a customizable metal layer and maybe a generally unpatterned solid layer of metal which may readily beconfigured by employing conventional lithography and removal of portionsof the metal layer by conventional etching, or other methods such asCMP.

Preferably one or more of metal layers 20, 22 and 24 may comprisepre-patterned electrically conductive paths 28, 30 and 32 respectively.The term “electrically conductive path” excludes semiconductorconnections and antifuses in series therewith. Preferably all or most ofeach metal layer 20, 22 and 24 which comprises pre-patternedelectrically conductive paths constitutes repeated sub-patterns.

Layer 26 and the conductive paths 32 on layer 24 together providecustomizable portions of the integrated circuit device, while theunderlying conductive paths 28 and 30 on respective layers 20 and 22cooperate with transistors in silicon layers adjacent thereto to providethe electrically programmable logic part of the integrated circuitdevice.

Reference is now made to FIG. 2, which is a more detailed illustrationof portions of the integrated circuit device of FIGS. 1A and 1Bincluding both customizable and programmable portions. FIG. 2 showsunpatterned layer 26 and thereunder patterned layer 24. On layer 24there are shown a plurality of bridges 40 communicating between adjacentvias 42, which in turn are connect to layer 26.

Layer 24 also includes sections of vias 44 which communicate betweenlayers 20 and 22 and layer 26. Vias 44 interconnect various electricallyprogrammable logic units, which are designated schematically as blocks46 and are typically located on and underlying layers 20 and 22 andtheir underlying silicon layers

Electrically programmable logic units 46 typically comprise conventionalfield programmable logic units, which may include, for example, RAMs,Flash Memories, PROMs and antifuse links.

FIG. 9 is a simplified table indicating part of the functionality of atypical logic unit 46, such as a RAM, having address inputs A and Bconnected to layer 26 by respective vias 44 which are labeled A and Band an output C, also connected to layer 26 by a via 44, which islabeled C.

It may be seen from FIG. 9 that output C has a different value b0, b1,b2 and b3 for each of four different combinations of inputs A and B. Thelogic unit 46 may thus be programmed by suitable selection of the valuesb0, b1, b2 and b3 output in response to the various input combinationsprovided to inputs A and B. Such logic unit has been found to be veryuseful in programmable logic and is known in the art as Look-Up-Table(LUT).

Reference is now made to FIG. 3, which is an illustration of thecircuitry of FIG. 2 following customization for one type offunctionality. It is seen that most of layer 26 has been removed,leaving only electrically conductive pathways 50, which interconnectvarious vias 42 and 44. FIG. 4, which is an illustration of thecircuitry of FIG. 2 following customization for another type offunctionality shows a different pattern of conductive pathways 50.

Reference is now made to FIG. 5, which is an equivalent circuitillustrating the circuitry of FIG. 3 following customization andprogramming for one type of functionality. FIG. 5 shows the logicfunction produced by the circuitry of FIG. 3 when all of the logic units46 thereof are programmed identically in accordance with the look-uptable shown therein. FIG. 6 shows that when all the logic units 46thereof are programmed in accordance with the look-up table showntherein, different from look-up table of FIG. 5, a different logicfunction results.

Reference is now made to FIG. 7, which is an equivalent circuitillustrating the circuitry of FIG. 4 following customization andprogramming for one type of functionality. FIG. 7 shows the logicfunction produced by the circuitry of FIG. 4 when the various logicunits are programmed in accordance with the look-up tables showntherein.

FIG. 8 shows that when the various logic units of FIG. 4 is programmedin accordance with the look-up tables shown therein differently from thelook-up tables of FIG. 7, a different logic function results.

In accordance with another preferred embodiment of the presentinvention, there is provided a customizable logic array device includinga substrate having at least one gate layer and typically at least first,second and third metal layers formed thereon, wherein the gate layerincludes a multiplicity of identical unit logic cells. It is appreciatedthat the customizable logic array device may be integrated into a largerdevice also formed on the same substrate.

The present invention also provides a customizable logic array deviceincluding an array of cells, the device having at least one transistorlayer, including a multiplicity of transistors, formed on a substrateand at least one interconnection layer which connects the transistors todefine the array of cells, each of the cells having a multiplicity ofinputs and at least one output.

There are preferably provided additional interconnection layers, atleast one of which is custom made to interconnect the inputs and outputsof the various cells to provide a custom logic function. Preferably atleast some of the cells are identical.

Reference is now made to FIG. 10, which illustrates a cell preferablyforming part of a gate layer of a logic array device constructed andoperative in accordance with a preferred embodiment of the presentinvention. The logic device preferably comprises an array of cells. Eachcell includes cell inputs 1040, 1042, 1044, 1046, 1050, 1052, 1054,1056, 1060, 1070, 1072, 1074, 1076, 1080, 1082, 1084, 1086, 1090, 1097,and cell outputs 1062, 1064, 1092, 1094, 1100, 1102, 1108. Each cellcomprising 3-input look-up tables (LUT3s), respectively designated byreference numerals 1010, 1012, 1014 and 1016. Coupled to a first inputof each look-up table, hereinafter referred to as a LUT input, is a2-input NAND gate. The NAND gates are designated by respective referencenumerals 1020, 1022, 1024 and 1026.

Alternatively, any other suitable type of logic gate, such as, forexample, a NOR, AND, OR, XOR or 3-input logic gate, may be employedinstead of a NAND gate.

Outputs of LUTs 1010 and 1012 are supplied as inputs to a multiplexer1030, while outputs of LUTs 1014 and 1016 are supplied as inputs to amultiplexer 1032. The outputs of multiplexers 1030 and 1032 are suppliedto a multiplexer 1034. Multiplexers 1030, 1032 and 1034 are preferablyinverting multiplexers, as shown.

A NAND fed four-input LUT may be realized by connecting respectiveinputs 1040, 1042, 1044 and 1046 of LUT 1014 and NAND gate 1024 torespective inputs 1050, 1052, 1054 and 1056 of LUT 1016 and NAND gate1026. The inputs of the resulting NAND fed four-input LUT are inputs1040, 1042, 1044 & 1046 and the select input to multiplexer 1032, whichis designated by reference numeral 1060. The output of the NAND fedfour-input LUT is the output of multiplexer 1032, which is designated byreference numeral 1062.

A NAND fed four-input LUT may be realized by connecting respectiveinputs 1070, 1072, 1074 and 1076 of LUT 1010 and NAND gate 1020 torespective inputs 1080, 1082, 1084 and 1086 of LUT 1012 and NAND gate1022. The inputs of the resulting NAND fed four-input LUT are inputs1070, 1072, 1074 & 1076 and the select input to multiplexer 1030, whichis designated by reference numeral 1090. The output of the NAND fedfour-input LUT is the output of multiplexer 1030, which is designated byreference numeral 1092.

It is further appreciated that if the output of LUT 1014, designated byreference numeral 1064, is connected to the select input 1060,multiplexer 1032 performs a NAND logic function on the output of LUT1014 and the output of LUT 1016, designated by reference numeral 1062.

Similarly, if the output of LUT 1010, designated by reference numeral1094, is connected to the select input 1090 of multiplexer 1030,multiplexer 1030 performs a NAND logic function on the output of LUT1010 and the output of LUT 1012, designated by reference numeral 1092.

It is appreciated that other logic functions may be generated bymultiplexers 1030 and 1032. For example, if input 1060 and output 1066are connected together, a NOR logic function is performed on outputs1064 and 1066, having an output at output 1062.

A NAND fed five-input LUT may be realized by connecting respectiveinputs 1040, 1042, 1044, 1046 and 1060 of one NAND fed four-input LUTwith inputs 1070, 1072, 1074, 1076 and 1090 of the other NAND fedfour-input LUT. The inputs of the resulting NAND fed five-input LUT areinputs 1040, 1042, 1044, 1046 and 1060 as well as the E select input tomultiplexer 1034, designated by reference numeral 1097. The output ofthe NAND fed five-input LUT is designated by reference numeral 1100.

It is additionally appreciated that if the output 1062 of multiplexer1032 is connected to input 1097, multiplexer 1034 performs a NAND logicfunction on the output 1092 of multiplexer 1030 and the output 1062 ofmultiplexer 1032.

It is further appreciated that if the output 1092 of multiplexer 1030 isconnected to input 1097, multiplexer 1034 performs a NOR logic functionon the output 1092 of multiplexer 1030 and the output 1062 ofmultiplexer 1032.

Preferably a flip flop 1102 is coupled to the output 1062 of multiplexer1032 and a flip flop 1104 is coupled to the output 1100 of multiplexer1034.

Additionally, an inverter 1106 is provided for selectableinterconnection to one of the cell outputs 1062, 1064, 1092, 1094, 1107,1108 and 1100. Inverter 1106 could be used to change the polarity of alogic signal to provide a desired logic function. Inverter 1106 couldalso be used to buffer certain signals to effectively drive a relativelyheavy load, such as in cases where a single output is supplied tomultiple inputs or along a relatively long interconnection path. It isappreciated that alternatively or additionally any other one or moresuitable logic gate, such as for example, a NAND, NOR, XOR or XNOR gate,may be provided in the cell.

It is appreciated that various interconnections between inputs andoutputs of various components of the cell described hereinabove andbetween inputs and outputs of various cells of the logic array arepreferably achieved by one or more selectably configurable overlyingmetal layers, which are preferably mask configurable. A permanentcustomized interconnect is thus provided.

Reference is now made to FIG. 11, which illustrates a cell preferablyforming part of a gate layer of a logic array device constructed andoperative in accordance with another preferred embodiment of the presentinvention. The cell of FIG. 11 is presently believed by the inventor tobe superior in certain respects to the cell of FIG. 10. The logic devicepreferably comprises an array of cells, each cell comprising 4-inputlook-up tables (LUTs), respectively designated by reference numerals1110, 1112, 1114 and 1116. Coupled to first and second inputs of each oflook-up tables 1110 and 1112, hereinafter referred to as a LUT inputs,is a 2-input NAND gate. The NAND gates are designated by respectivereference numerals 1120, 1122, 1124 and 1126.

Alternatively, any other suitable type of logic gate, such as, forexample, a NOR, AND, OR, XOR or 3-input logic gate may be employedinstead of the NAND gates.

Outputs of LUTs 110 and 1112 are supplied as inputs to a multiplexer1130, while outputs of LUTs 1114 and 1116 are supplied as inputs to amultiplexer 1132. The outputs of multiplexers 1130 and 1132 are suppliedto a multiplexer 1134. Multiplexers 1130, 1132 and 1134 are preferablyinverting multiplexers, as shown.

A four-input LUT may be realized by connecting respective inputs 1140,1142, and 1144 and 1146 of the NAND gates 1124 and 1126, and thenconnecting inputs 1140, 1144, and 1148 of LUT 1114 to respective inputs1150, 1152 and 1154 of LUT 1116. The inputs of the resulting four-inputLUT are inputs 1140, 1144 & 1148 and the select input to multiplexer1132, which is designated by reference numeral 1160. The output of thefour-input LUT is the output of multiplexer 1132, which is designated byreference numeral 1162.

A four-input LUT may be realized by connecting the inputs 1170, 1172,and 1174, 1176 of NAND gates 1120 and 1122, and then connecting inputs1170, 1174 and 1178 of LUT 1110 to respective inputs 1180, 1182 and 1184of LUT 1112. The inputs of the resulting four-input LUT are inputs 1170,1174 & 1178 and the inputs to multiplexer 1130, which is designated byreference numeral 1190. The output of the four-input LUT is the outputof multiplexer 1130, which is designated by reference numeral 1192.

It is further appreciated that if the output of LUT 1116, designated byreference numeral 1166, is connected to the select input 1160,multiplexer 1132 performs a NAND logic function on the output of LUT1114 and the output of LUT 1116.

Similarly, if the output of LUT 1112, designated by reference numeral1196, is connected to the select input 1190 of multiplexer 1130,multiplexer 1130 performs a NAND logic function on the output of LUT1110 and the output of LUT 1112. It is appreciated that other logicfunctions may be generated by multiplexers 1130 and 1132. For example,if input 1160 and output 1164 are connected together, a NOR logicfunction is performed on outputs 1164 and 1166, having an output atoutput 1162.

It is additionally appreciated that if the output 1162 of multiplexer1132 is connected to input 1197, multiplexer 1134 performs a NOR logicfunction on the output 1192 of multiplexer 1130 and the output 1162 ofmultiplexer 1132.

It is further appreciated that if the output 1192 of multiplexer 1130 isconnected to input 1197, multiplexer 1134 performs a NAND logic functionon the output 1192 of multiplexer 1130 and the output 1162 ofmultiplexer 1132.

Preferably a flip flop 1199 is coupled to the output 1162 of multiplexer1132 and a flip flop 1195 is coupled to the output 1198 of multiplexer1134.

Additionally an inverter 1193 is provided for selectable interconnectionto one of the cell outputs 1162, 1166, 1192, 1196, 1191, 1189 and 1198.Inverter 1193 could be used to change the polarity of a logic signal toprovide a desired logic function. Inverter 1193 could also be used tobuffer certain signals to effectively drive a relatively heavy load,such as in cases where a single output is supplied to multiple inputs oralong a relatively long interconnection path. It is appreciated thatalternatively or additionally any other one or more suitable logic gate,such as for example, a NAND, NOR, XOR or XNOR gate, may be provided inthe cell.

It is appreciated that various interconnections between inputs andoutputs of various components of the cell described hereinabove andbetween inputs and outputs of various cells of the logic array arepreferably achieved by one or more selectably configurable overlyingmetal layers, which are preferably mask configurable. A permanentcustomized interconnect is thus provided.

Reference is now made to FIG. 12, which is an illustration of aplurality of the cells of FIG. 10,_(—)which constitute a portion of alogic array, preferably a customizable logic array, in accordance with apreferred embodiment of the present invention. It is appreciated thatalternatively, FIG. 12 could include a plurality of the cells of FIG.11.

Reference is now made to FIG. 13, which is a simplified illustration ofa gate layer of a plurality of logic cells_(—)which constitute a portionof a logic array and incorporate a clock tree in accordance with apreferred embodiment of the present invention.

As seen in FIG. 13, a clock tree distribution circuit, generallyindicated by reference numeral 1200, provides clock signals from a clocksignal source (not shown) via an inverter 1202 to each pair offlip-flops 1204 and 1206 in each logic cell 1208. Although the logiccell of FIG. 10 is shown, it is appreciated that alternatively andpreferably, the logic cell of FIG. 11 may be employed. It is appreciatedthat the structure of FIG. 13 is very distinct from the prior artwherein a clock tree distribution circuit is implemented in at least onecustom interconnection layer.

In accordance with a preferred embodiment of the present invention,three metal layers, such as metal 1, metal 2 and metal 3 are typicallystandard. Three additional metal layers, such as metal 4, metal 5 andmetal 6 may be used for circuit customization for a specificapplication. In logic arrays of this type, it is often desirable toprovide a multiplicity of clock domains. Each such clock domain requiresits own clock distribution tree. Connection of the clock domains can bereadily achieved by suitable customization of an upper metal layer, suchas metal 6.

It is appreciated that the number of cells connected to a givendistribution tree may vary greatly, from tens of cells to thousands ofcells. This variation can be accommodated easily using the structure ofthe present invention.

It is appreciated that each flip flop in each cell has approximately thesame interconnection load on the clock distribution tree.

Multiple phase lock loops (PLLs) may be employed to adjust the phase ofeach clock tree with respect to an external clock.

Reference is now made to FIG. 14, which is a simplified illustration ofa gate layer of a plurality of logic cells which constitute a portion ofa logic array and incorporate a scan chain in accordance with apreferred embodiment of the present invention._(—)Although the cells ofFIG. 10 are shown in FIG. 14, it is appreciated that alternatively, thecells of FIG. 11 may be employed.

In the prior art scan chains, which provide test coverage for integratedcircuits, are known to involve not insignificant overhead in terms bothof real estate and performance. Conventionally, scan chains are usuallyinserted either as part of a specific circuit design or during postprocessing.

In accordance with the present invention, as shown in FIG. 14, a scanchain 1300 is implemented as part of the basic structure of a logic cellarray. The invention thus obviates the need to insert scan chains eitheras part of a specific circuit design or during post processing. Amultiplicity of scan chains can be integrated in a logic cell array inaccordance with a preferred embodiment of the present invention.

Connection of the scan chains can be readily achieved by suitablecustomization of an upper metal layer, such as metal 6.

In the embodiment of FIG. 14, multiplexers 1032 and 1034 are preferablyreplaced by corresponding 3-state multiplexers 1302 and 1304. A pair of3-state inverters 1306 and 1308 are provided in each cell and areconnected as shown. During normal operation of the array, the scansignal is a logic “low” or “0”, thus enabling multiplexers 1302 and 1304and disabling inverters 1306 and 1308.

During testing of the array, the scan signal is a logic “high” or “1”and the multiplexers 1302 and 1304 are disabled while the inverters 1306and 1308 are enabled. In such a scan mode the output of flip flop 1102of a given cell is fed to the input of flip flop 1104 of that cell andthe output of flip flop 1104 is fed to the input of flip flop 1102 ofthe adjacent cell, thus creating a scan chain.

It is appreciated that additional multiplexers may also be employed inthis embodiment.

FIGS. 15–9 illustrate variations of repeating routing patterns of thetop metal layers of the cell array. These patterns are repeated multipletimes in an actual circuit. The pre-customized circuits may or may notform a part of a larger integrated circuit device. For reasons ofpracticality, an entire semiconductor device including such circuitscannot be illustrated to a resolution which enables the routingstructure thereof to be discerned.

Reference is now made to FIG. 15, which is a pictorial illustration ofthe lower two of the top three metal layers of a cell array deviceconstructed and operative in accordance with a preferred embodiment ofthe present invention, prior to customization and to FIG. 17 which is aschematic illustration corresponding thereto.

In accordance with a preferred embodiment of the invention, the cellarray device of FIG. 15, when customized, includes a total of sevenmetal layers, identified as M1–M7, the top metal layer being identifiedas M7. Metal layers M1–M3 are employed for constructing logic units orcells. Layers M4–M7 are employed for routing signals between cells.Generally metal layers M6 and M7 are employed for relatively short orlocal routing paths, while metal layers M4 and M5 are employed for longor global routing. Typically metal layers M4 and M6 provide routinggenerally in North-South directions, in the sense of FIG. 17, whilemetal layers M5 and M7 provide routing generally in East-Westdirections.

FIGS. 15–9 shows various arrangements which provide such routing and inwhich metal layers M1–M6 are fixed. Customization is carried out only onvias connecting metal layers M6 and M7, here termed M6M7 vias, or onboth M6M7 vias and on metal layer M7.

In FIG. 15, the top metal layer M7 is not shown, inasmuch as this metallayer is added during customization, as will be described hereinbelowwith reference to FIG. 16 and to FIG. 18, which is a schematicillustration corresponding thereto.

The basic structure shown in FIG. 15 comprises an M6 metal layer whichcomprises multiple spaced bands 2010 of parallel evenly spaced metalstrips 2012, the center lines of which are preferably separated one fromthe other by a distance “a”. At a given periodicity, typically everytwenty strips 2012, a plurality of pairs 2014 of short strips 2016 isprovided. The number of pairs 2014 of short strips 2016 and their lengthis a matter of design choice. Strips 2012 and 2016 are shown runningNorth-South.

Underlying the M6 metal layer is an M5 metal layer comprising parallelevenly spaced metal strips 2022 extending East-West in the sense of FIG.15 in bands 2010. In the illustrated embodiment of FIG. 15, strips 2022each underlie three pairs 2014 of short strips 2016 and are eachconnected at opposite ends thereof by means of an M5M6 via 2024 to astrip 2016. It is noted that adjacent ones of strips 2022 begin and endat strips 2016 of different pairs 2014, such that each pair 2014 ofstrips 2016 is connected to strips 2022 extending along a differentaxis. It is appreciated that each strip 2016 preferably is connected toonly a single strip 2022.

It is appreciated that the embodiment of FIG. 15 is merely exemplary inthat, for example, each strip 2016 may overlie more than three strips2022 and thus each strip 2022 may underlie more than three pairs 2014 ofshort strips 2016.

Reference is now made to FIG. 16, which is a pictorial illustrationcorresponding to FIG. 15 following customization thereof. It is seenthat in FIG. 16 an M7 layer is added for customization of the cellarray. The M7 layer may include a bridge 2030 connected by M6M7 vias2032 to adjacent strips 2016 of a pair 2014, thus effectively connectingtwo strips 2022 lying along the same elongate axis.

The M7 layer may also provide another type of connection, such asconnections 2036 between one of strips 2016 and a strip 2012, by meansof M6M7 vias 2038. This type of connection provides a circuit connectionbetween a strip 2022 and a strip 2012.

The M7 layer may additionally provide a further type of connection, suchas connections 2040 between strips 2012 in two adjacent bands 2010, bymeans of M6M7 vias 2042. This type of connection provides a North-Southcircuit connection by means of strips 2012.

It is appreciated that the customized structure of FIGS. 16 & 18 enablesa signal received along a strip 2022 to be conveyed in an East-Westdirection via strips 2022 and to be coupled to a strip 2012 at anappropriate East-West location. In accordance with a preferredembodiment of the present invention, in the customization of thestructure of FIGS. 15 & 17, in each band 2010, a single elongate axis isemployed for placement of bridges 2030 for interconnecting underlyingstrips 2022 to provide East-West routing and for placement ofconnections 2036 between strip 2012 and strip 2022 for long routing ofsignals in East-West directions, as shown in FIGS. 16 & 18. The otherparallel East-West elongate axes are employed for shorter East-Westrouting.

Reference is now made to FIG. 19, which is a schematic illustrationcorresponding to FIGS. 15 & 17 but showing a variation in thearrangement of the lowest of the three metal layers. This variation isprovided principally to help overcome problems of signal crosstalkbetween signals traveling alongside each other along strips 2022 over arelatively long distance. In the arrangement of FIG. 19, each strip2044, corresponding to strip 2022 (FIGS. 15 & 17) shifts its elongateaxis at least one location therealong. As seen in FIG. 20, customizationof the embodiment of FIG. 19 may include bridges 2046 between adjacentstrips 2016 of a pair 2014, which provide a continuation of East-Westrouting and also produce a switch between the longitudinal axes of twoadjacent strips 2044, thus decreasing crosstalk. This is accomplished bylimiting the distance that signals travel alongside each other by meansof switching and mixing the order of the long routing conductors.

It is appreciated that although the shift is shown embodied in the M5metal layer, it may be carried out using appropriate vias and anunderlying metal layer.

Reference is now made to FIG. 21, which is a schematic illustrationcorresponding to FIGS. 15 & 17 but showing a variation in thearrangement of the middle of the top three metal layers. Thisarrangement is provided in order to take into account often oversizestrips in M7 layers which, due to their size, could not be placed sideby side to provide bridges for adjacent strips 2012 without creating ashort circuit therebetween.

The arrangement of FIG. 21 is distinguished from that of FIGS. 15 & 17in that whereas in FIGS. 15 & 17, strips 2012 of each band 2010 allterminate in a line, defining an elongate edge of band 2010, which isspaced from the corresponding elongate edge of an adjacent band 2010, inFIG. 21, the strips 2052 of adjacent bands 2054 do not terminate at thesame North-South location. Thus, in the embodiment of FIG. 21, thestrips of adjacent bands 2054 are interlaced. As seen in FIG. 22,bridges 2056 between strips 2052 of adjacent bands 2054 are thus offsetfrom each other, providing ample spacing therebetween notwithstandingthe relatively large width of the bridges.

Reference is now made to FIGS. 23A and 23B, which together show aschematic illustration of the lower four of the top five metal layers ofa cell array device constructed and operative in accordance with anotherpreferred embodiment of the present invention, prior to customization.

In accordance with a preferred embodiment of the invention, the cellarray device of FIGS. 23A and 23B, when customized, includes a total ofseven metal layers, identified as M1–M7, the top metal layer beingidentified as M7. In FIGS. 23A and 23B, the top metal layer M7 is notshown, inasmuch as this metal layer is added during customization, aswill be described hereinbelow with reference to FIGS. 24A and 24B.

The basic structure shown in FIGS. 23A and 23B comprises a M6 metallayer which comprises multiple spaced bands 2110 of parallel evenlyspaced metal strips 2112, the center lines of which are preferablyseparated one from the other by a distance “a”. Pair 2114 providesconnections to long routing conductors in North-South directions, whichare implemented by M4 strips 2132 and 2133 as described hereinbelow.

Underlying the M6 metal layer typically is an M5 metal layer comprisingparallel evenly spaced metal strips 2122 extending East-West in thesense of FIGS. 23A and 23B in bands 2110. In the illustrated embodimentof FIGS. 23A and 23B, strips 2122 each extend across three pairs 2115 ofshort strips 2117 and are each connected at opposite ends thereof bymeans of an M5M6 via 2124 to a strip 2117. Pair 2115 providesconnections to long routing conductors in East-West directions.

It is noted that adjacent ones of strips 2122 begin and end at strips2117 of different pairs 2115, such that each pair 2115 of strips 2117 isconnected to strips 2122 extending along a different axis. It isappreciated that each strip 2117 preferably is connected to only asingle strip 2122. The portion of the pattern which provides longrouting conductors in East-West directions along M5 strips 2122 isdescribed hereinabove with reference to FIGS. 15 & 17. The M5 layer alsocomprises a plurality of bridge elements 2126 which extend parallel tostrips 2122.

Underlying the M5 metal layer there is provided an M4 metal layerpreferably comprising evenly spaced stepped strips 2132 and straightstrips 2133, extending generally North-South in the sense of FIGS. 23Aand 23B across multiple bands 2110. At a given periodicity, typicallyevery four to seven strips 2112, a plurality of pairs 2114 of coaxialshort strips 2116 is provided.

FIGS. 23A and 23B show a single band 2111 of parallel stepped strips2132 and straight strips 2133. Multiple similar bands 2111 extending inthe North-South directions are provided in a semiconductor device.Strips 2112 and 2116 are shown running North-South. The Southmost end ofeach strip 2132 is connected by an M4M5 via 2134 and an M5M6 via 2136 toa Northmost end of a strip 2116 of a pair 2114. A facing end of a secondstrip 2116 of pair 2114 is connected by an M5M6 via 2136 to an Westmostend of a bridge element 2126, the Eastmost end of which is connected byan M4M5 via 2134 to a Northmost end of a strip 2133.

The Southmost end of a strip 2133 is connected by an M3M4 via 2138 tothe Northmost end of an L-shaped tunnel 2140 embodied in an M3 metallayer. The South-Westmost end of tunnel 2140 is connected by an M3M4 via2138 to the Northmost end of a strip 2132.

Reference is now made to FIGS. 24A and 24B, which together show aschematic illustration corresponding to FIGS. 23A and 23B followingcustomization thereof. It is seen that in FIGS. 24A and 24B an M7 layeris added for customization of the cell array. The M7 layer may include abridge 2141 connected by M6M7 vias 2142 to adjacent strips 2116 of apair 2114, thus effectively connecting two strips 2132.

The M7 layer may also provide another type of connection, such asconnections 2153 between one of strips 2116 and a strip 2112, by meansof M6M7 vias 2142. This type of connection provides a circuit connectionbetween a strip 2132 and a strip 2112 employing short strip 2116,thereby to route signals over a relatively long distance in North-Southdirections. It is appreciated that the arrangement of FIGS. 24A and 24Benables all connections to North-South M4 strips 2132 and 2133 to bemade generally along one North-South axis 2114.

The M7 layer may also provide a further type of connection, such asconnections 2150 between strips 2112 in two adjacent bands 2110, bymeans of M6M7 vias 2142. This type of connection provides a North-Southcircuit connection by means of strips 2112. Connections 2152 betweenstrips 2112 in the same band and a connection 2155 between strip 2117and strips 2112 in the same band may also be provided. It is thusappreciated that the customized structure of FIGS. 24A and 24B enables asignal received along a strip 2122 to be conveyed in an East-Westdirection via strips 2122 and to be coupled to a strip 2132 at anappropriate East-West location by properly employing the M7 layer andthe M6M7 vias 2142 using M6 strips 2112, 2116 and 2117. FIGS. 24A and24B show such a structure employing M7 connections 2150, 2153 and 2155.

Reference is now made to FIGS. 25A, 25B, and 25C, which together show aschematic illustration corresponding to FIGS. 23A and 23B but showing avariation in the arrangement of the M3, M4 and M5 metal layers. Thisvariation is provided principally to help overcome problems of signalcrosstalk between signals traveling alongside each other along strips2132 over a relatively long distance. In the arrangement of FIGS. 25A,25B, and 25C, there is provided in the M4 metal layer an arrangementwhich enables shifting of the elongate axis of North-South extendingconductors in both East and West directions, thus enabling crosstalk tobe decreased by appropriate switching of the order of strips2132._(—)This is accomplished by limiting the distance that signalstravel alongside each other by means of switching and mixing the orderof the long routing conductors.

FIGS. 26A, 26B, and 26C show the configuration of FIGS. 25A, 25B, and25C following exemplary customization by the addition of a via M6M7 2142and M7 layers 2150 and 2153.

Reference is now made to FIG. 27, which is a schematic illustrationcorresponding to FIGS. 15 & 17 with additional bridges 2160 in the M6layer extending perpendicular to metal strips 2161, which correspond tostrips 2012 in the embodiment of FIGS. 15 & 17.

FIG. 27 together with FIGS. 28 and 29, which is referred to hereinbelow,illustrate another preferred embodiment of the present invention whereincustomization is effected only in M6M7 vias. This embodiment providessavings in customization tooling by keeping the M7 metal layer fixed.

FIG. 28 is a schematic illustration corresponding to FIG. 27 and showingthe top metal layer M7, prior to customization. As seen in FIG. 28, theM7 layer includes bridges 2162 extending North-South and relatively longstrips 2164 extending East-West. Strips 2164 partially overlie bridges2160 shown in FIG. 27 and bridges 2162 partially overlie strips 2161shown in FIG. 27.

FIG. 29 is a schematic illustration corresponding to FIG. 28 having viacustomization. It is seen that M6M7 vias 2166 interconnect strips 2161(FIG. 27) by employing bridges 2162 as shown in (FIG. 28) in order toprovide North-South routing. Other M6M7 vias 2168 interconnect strips2164 (FIG. 28) by employing bridges 2160 (FIG. 27) in order to provideEast-West routing. Additional M6M7 vias 2170 interconnect strips 2161shown in FIG. 27, with strips 2164 shown in FIG. 28, in order tointerconnect the East-West routing with the North-South routing.

The following drawings, FIGS. 30 to 36, show typical designs of thevarious layers constructed and operative in accordance with a preferredembodiment of the present invention.

Reference is now made to FIG. 30, which illustrates a single routingcell unit 2200, comprising layers M4 to M6, constructed and operative inaccordance with a preferred embodiment of the present invention.Preferably, the cell unit 2200 overlays a corresponding logic cell unitsuch as 1208, forming a cell array in accordance with a preferredembodiment of the invention. The routing cell unit 2200, illustrated inFIG. 30, comprises 3 I/O contacts 2202, 2204 and 2206 to the cell inputsand the cell outputs of the underlying logic cell (not shown) at layerM3. The routing cell unit 2200 in FIG. 30 also shows strips 2044/2022,typically located in an E-W direction, and corresponding to the strips2044/2022 shown in FIGS. 17 and 19. The cell unit 2200 shows the strips2044/2022 overlap the N-S strips 2132 and 2133, as described hereinabovewith respect to FIGS. 23A and B and 25A–C. FIG. 31 shows a routing cellunit 2208, of similar construction to routing cell unit 2200 of FIG. 30,but without the I/O contacts 2202, 2204 and 2206.

Reference is now made to FIG. 32, which illustrates typical routingconnections in the M3 and M4 layers, and the M3M4 via and M4M5 vialayers, of the cell unit 2200. The routing connections shown in FIG. 32,correspond to the straight strips 2133 and the stepped strips 2132 shownin FIGS. 23A and B and 25A–C. FIG. 32 also shows the L-shaped tunnel2140, embodied in the M3 layer, connecting the Southmost end of strip2133 to the Northmost end of strip 2132. FIG. 32 further illustrates aseries of S-shaped contacts 2210, 2212, 2214 and 2216, in layer M4, forproviding a shift between strips 2044 of layer M5 using the M4M5 vias,as described hereinabove with respect to FIG. 19. The contacts 2210,2212, 2214 and 2216, help to reduce the crosstalk between parallelstrips, as discussed hereinabove with reference to FIG. 19. FIG. 32 alsoshows multiple bands 2217, 2219, 2221, 2223 and 2225, which run in theNorth-South direction, corresponding to the band 2111 of FIGS. 23A andB.

Reference is now made to FIG. 33, which illustrates an M5 layercorresponding to the arrangement described hereinabove with respect toFIG. 19. The strips 2044 in the E-W direction, shown in FIG. 33,correspond to the strips 2044 of FIG. 33. FIG. 33 also shows bridgingelements 2126 between strips 2116 and 2133 of FIGS. 23A and B and 25A–C,and a series of M4M5 vias 2134.

Reference is now made to FIG. 34, which shows the M6 layer with viasM5M6, corresponding to the M6 layers of FIGS. 23A and B. Additionally,FIG. 34 shows the strips 2016/2117 and 2012/2112 corresponding to thestrips in FIGS. 15 and 23A and B, and strip 2116 corresponding to thestrips in FIGS. 23A and B. FIG. 34 also shows typical I/O connections2230, 2232, 2234, 2236 and 2238.

Reference is now made to FIG. 35, and shows a typical arrangement of 16cells 2200, as shown in FIG. 30, of M3 and M4 layers, and the M3M4 viaand M4M5 via layers, in a 4×4 matrix, in accordance with a preferredembodiment of the present invention. FIG. 35 also shows the strips 2132and 2133, corresponding to strips 2132 and 2133 of FIGS. 23A and B and25A–C. FIG. 35 further illustrates a series of S-shaped contacts 2240,2242, 2244, 2246 in layer M4, as described hereinabove with respect toFIG. 32, for providing a shift between strip 2044 of layer M5 using theM4M5 vias, as described hereinabove with respect to FIG. 19.

Reference is now made to FIG. 36, which illustrates an M5 layercomprising a 4×4 matrix of 16 cells 2200, in accordance with a preferredembodiment of the present invention. The M5 layer comprises strips2044/2022, as shown in FIGS. 17 and 19, and also shows typical bridges2250 and 2252, corresponding to the bridge 2126 of FIGS. 25A–C. Thebridge 2250 is in the East direction and the bridge 2252 is in the Westdirection.

Reference is now made to FIG. 37, which illustrates an M6 layer and M5M6via layer of a 4×4 cell 2200, as shown in FIG. 30, matrix, in accordancewith a preferred embodiment of the present invention. The M6 layertypically comprises multiple spaced bands 2260, 2262, 2264 and 2266,which run in the East-West direction. The multiple cells 2260 to 2266correspond to the multiple spaced bands 2010 of FIG. 15, and to the E-Wbands 2110 of FIGS. 23A and B.

Reference is now made to FIG. 38, which illustrates the layers M3, M4,M5, M6 and M7 in a 4×4 cell matrix, in accordance with a preferredembodiment of the present invention.

It is known in the art that as circuit complexity increases, test timebecomes an important factor in device cost. Thus, in order to reducetest time and test costs, an easy-to-test functionality is loaded intothe Look-Up-Tables of a cell array, in accordance with a preferredembodiment of the present invention. Such easy-to-test functionality mayinclude XOR logic or NXOR logic.

An advantage of using XOR or NXOR logic is that it propagates any singlechange in the input to the output regardless of the logic state of theother input signals. NAND logic, for example, allows the input change topropagate only if the other inputs are at a high “1”. This results inthe requirement of 4 test vectors to test a NAND-3 device, including itsinput connections, versus 2 test vectors to test a XOR-3, including itsinput connections. Since many designs have 4 levels of logic betweenFlip/Flop (F/F) devices, the number of test vectors required to test acomplex circuit could thus be reduced by an order of magnitude usingthis technique.

The test process includes loading all LUTs in all cells in the cellarray (not shown) with a pattern equivalent to an XOR or NXOR, and run astandard ATPG program, such as provided by Mentor Graphics Corporation,Branch Office, San Jose, Calif., USA, or Synopsys, on the modifieddesign.

Reference is now made to FIG. 39, which illustrates a cell 3200 calledeCell preferably forming part of a gate layer of a cell array deviceconstructed and operative in accordance with yet another preferredembodiment of the present invention. It is appreciated that cell 3200 isthe schematic equivalent of the gate layer underlying theinterconnection layer of the routing cell unit 2200, illustrated in FIG.30. The logic array device preferably comprises an array of cells, eachcell typically including two 3-input look-up tables (LUT-3),respectively designated by reference numerals 3210 and 3212, amultiplexer 3211 and a scanned Dflip/Flop (S-DF/F) unit 3241.

Additionally, the cell unit 3200 comprises cell inputs 3262, 3216, 3218,3220, 3222, 3226, 3228, 3230, 3232, and two inverters inputs 3265 and3267. Additionally, the cell unit 3200 comprises cell outputs 3263,3264, 3266 and 3254. The interconnections between various cells inputsand outputs are customized for any custom device by the metalinterconnection layers preferably using interconnection structures suchas 2200. Additionally the cell unit 3200 includes jumper connections3202, 3204 3206 and 3208 for providing cell-customization connectingcell input and internal connections between the various components ofthe cell 3200. In accordance with a preferred embodiment of the presentinvention, the jumper connections 3202, 3204, 3206 and 3208 arecustomizable, so as to allow, for example, connecting the output signalof the LUT device 3212 to the multiplexer unit 3211. For such a case,the cell 3200 operates in a similar fashion to the unit describedhereinabove (FIG. 10).

LUT 3210 includes 4 input lines 3216 (XA), 3218 (XB), 3220 (XC1) and3222 (XC2). A first 2-input NAND gate 3224 couples the input lines 3220and 3224 to the LUT 3210. Similarly, LUT 3212 receives input signalsalong lines 3226 (YA), 3228 (YB), 3230 (YC1) and 3232 (YC2) and a second2-input NAND gate 3234 couples the inputs 3230 and 3232 to the LUT 3212.

The output from LUT 3210 is provided to a first input 3236 of themultiplexer 3211. The multiplexer 3211 also receives input signals on asecond input line 3240. The multiplexer 3211 provides output signals toa scanned Dflip/Flop (S-DF/F) unit 3241 comprising a multiplexer 3242and a Dflip/Flop (DF/F) unit 3244.

The scanned Dflip/Flop (S-DF/F) unit 3241 is used for providing the testfeature ATPG (Automatic Test Program Generation), as is known in theart. Thus, an array of cells, such as cells 3200, includes a built-inscan chain for all flip-flop devices to support a full scan ATPG.

The scanned Dflip/Flop (S-DF/F) unit 3241 receives signals on input line3246, from a previous DF/F circuit and outputs signals to the followingscan circuit on line 3248. The DF/F 3244 receives clock input signals3250 (CK) and 3252 (CKB).

The output from cell 3200, in the memory mode, is read on line 3254 (DB)when the Read-Enable signal 3256 (REN) operates on the 3-state inverter3258, as explained hereinbelow.

The cell 3200 also includes 2 inverters 3260 and 3269, having cellinputs 3265 and 3267 and outputs 3264 and 3266, respectively.

Reference is now made to FIG. 40, which shows another preferred routingcell unit 3201 overlaying cell 3200, in accordance with a preferredembodiment of the present invention. Routing cell 3201 utilizes the twotop metal layers M5, M6 and the via layer between M5M6. Routing cell3201 also includes jumper connections for providing programmableconnections between components of the cell 3200, for example, themultiplexer 3211 and the LUT 3212 (FIG. 39), constructed and operativein accordance with a preferred embodiment of the present invention.

FIG. 40 shows the layout of the connection bars 3272, 3274, 3276 and3278, which corresponds to the jumper connections 3202, 3204, 3206 and3208, respectively, in FIG. 39. By appropriately placing a viaconnection 3280 under connection bar 3272, various connections may bemade to provide a required input to the inverter 3258 and/or to theinverter 3260 (FIG. 39). By means of the via connections such as thatshown by 3280 to the bar 3272, one of the signals MN or QN may beoutputted to the inverter 3258 and/or to the inverter 3260 (FIG. 39).FIG. 40 specifically shows QN connected to I1, the input to inverter3260.

Connection bars 3272 and 3274 preferably provide the functionality ofproviding drive to the output of one or two of the cell internal signalsMN, QN, YN, and YC. Furthermore, the connection bar 3278 jumper 3208 inFIG. 39) provides the function of allowing pull-up of the inputs MS,XC2, YC1, XB and I1.

In addition, the connection bar 3276 (jumper 3206 in FIG. 39) allowsconnecting the input signal M0 to the multiplexer 3211. This allowsmultiplexer 3211 to be used as a 2-input logic function. As shown inFIG. 39, jumper 3206 (connection bar 3276 in FIG. 40) allows theconnection of signals YN, XB, VDD, YC, MS, or I1 to the M0 (3240) inputof multiplexer 3211.

Furthermore, if YN is connected to input 3240 of multiplexer 3211 and toinput I1, and signal I1N is connected to the select MS 3262 input ofmultiplexer 3211, then multiplexer 3211 becomes a logic NOR between XNand YN.

A further example of the use of the multiplexer 3211 as a 2-input logicfunction, includes connecting YN to input 3240 of multiplexer 3211, andto input 3262. In this case, multiplexer 3211 becomes a NAND logic gatebetween XN and YN.

Still yet a further example of the use of the connection bar 3274 andthe multiplexer 3211, is to provide an enabled Flip/Flop (F/F) or setF/F. For example, for an enabled F/F, using bar 3274 to connect QN toinput 3240 (M0 input in FIG. 39); the input MS 3262 becomes the F/Fenable signal.

It is further appreciated that the inverters 3260 and 3269 as shown inFIG. 39, have different drive strengths. Proper selection of loading anddrive strength provides performance advantages not available fromequivalent structures with the same drive strength.

It is appreciated that in the following schematic drawings, the drawingsinclude the transistor sizes. The transistor sizes are bases on 0.18 μMtechnology. In general, the “upper” number indicates the diffusion widthof the p-transistor. The “lower” number indicates the diffusion width ofthe n-transistor. The poly gate is assumed to be 0.18 μM unlessspecifically indicated different sizes with a “/”. It is appreciatedthat different transistor sizes may be appropriate to other techniques.

Reference is now made to FIG. 41, which shows a detailed configurationof a LUT-3 device 3300, constructed and operative in accordance with apreferred embodiment of the present invention. The LUT-3 device 3300 maybe used as the LUT devices 3210 and 3212 shown in FIG. 39. The LUT-3device 3300 comprises a memory section 3310 and a decoder section 3311.The memory section 3310 includes a set of 8 RAM cells 3320A–320H,constructed and operative in accordance with a preferred embodiment ofthe present invention. The decoder section 3311 comprises an “upper”decoder unit 3312 and a “lower” decoder unit 3313. The “upper” decoderunit 3312 includes 4 transistor pairs 3314A–314D, wherein eachtransistor pair comprises 2 n-transistors connected in series.Similarly, the “lower” decoder unit 3313 comprises 4 transistor pairs3314E–314H, wherein each transistor pair includes 2 n-transistorsconnected in series, as shown in FIG. 41.

The output signals from the “upper” decoder unit 3312 are applied alongan output line 3316 to an “upper” sense amplifier unit 3320. The outputfrom the “upper” amplifier unit 3320 is then applied to an “upper”transmission gate 3322. Similarly, the “lower” decoder unit 3313 appliesits output signals to a “lower” sense amplifier unit 3324 via an outputline 3318. The output from the “lower” amplifier unit 3324 is inputtedto a “lower” transmission gate 3326.

The LUT-3 device 3300 also comprises an inverter section 3330 whichapplies the required gate signals to the upper and lower decoder units3312 and 3313, and to the upper and lower transmission gates 3322 and3326. The inverter section 3330 comprises a set of inverters 3331A–331Cfor creating both polarities of the inputs A, B and C. The LUT-3 device3300 receives input signals A, B, and C, which are also inverted tosignals AB, BB, and CB, respectively. The output signals from invertersection 3330 are dependent on a polarity of the input signals A, B, C.The signals A, AB, B and BB are applied as gate signals to the decodersunits 3312 and 3313, as shown in FIG. 41. Thus, the output signals 3316and 3318 are dependent on the content of the RAM cell selected by A, AB,B and BB, as described hereinbelow.

The signals C and CB are applied to transmission gates 3322 and 3324, asshown in FIG. 41.

Each RAM cell receives 3 input signals comprising Word Lines WR0, WR1and bit lines BIT0–BT7 and BIT0B to BIT7B, as shown in FIG. 41 anddescribed hereinbelow.

The respective output signals AB, A, BB and B, from the inverter section3330 are applied to the gates of the n-transistors of the decoder units3312 and 3313, as shown in FIG. 41. These gate signals AB, A, BB and B,decode and/or select one of the 4 output signals, R0–R3 and R4–R7, fromeach of the decoder units 3312 and 3314

The C input signal is applied to transmission gates 3322 and 3324 inorder to select which one of the 2 sensed signals 3316 or 3318 is to beoutputted.

The output signal 3328, from the respective transmission gate,represents the output signal, XN or YN, from the LUT 3210 or 3212 inFIG. 39.

It is appreciated that a unique feature of the decoder circuit 3311 isits ability to provide a very high-speed response to the C input and astandard speed response to A and B inputs.

In most designs, a few circuit paths are on the critical path of thecircuit. Accelerating the transition speed of those circuits increasesthe speed of the entire design. It is appreciated that in accordancewith a preferred embodiment of the present invention, including one ofthe 3 logically equivalent inputs with fast response (signal C) enablesthe acceleration of the critical path, and therefore the acceleration ofthe operation of the LUT.

Reference is now made to FIG. 42, which is a schematic drawing of asingle RAM cell, such as RAM cell 3320A of FIG. 41.

The RAM cell 3220A is conventional and known in the art as a“6-transistor RAM cell”. The RAM cell 3320A comprises 2 n-transistors3400 and 3402, and a data storage section comprising 2 inverters builtby transistors 3406 and 3408. The inverters are connected in a“back-to-back” fashion, as is known in the art.

In operation, a gate input signal to the transistors 3400 and 3402 isreceived on Word Line WL (3404). When the gate signal WL is high, thetransistors 3400 and 3402 are “open” and allow the input data on linesBL (3407) and BLB (3410) to be stored in the “storage” section. When WLis low, the transistors 3400 and 3402 are closed and input data does noteffect the inverters built by transistors 3406 and 3408. Thus, thetransistors 3406 and 3408 “remember” their previous state and the storeddata may be read out onto output line R (3412).

Reference is now made to FIG. 43, which shows a typical layout of asingle cell 3200 of FIG. 39. The cell 3200 comprises a column 3502 ofeight RAM cells and a column 3504 of 8-RAM cells of LUT 3210 and of LUT3212, (FIG. 39).

In the preferred embodiment of the present invention, the 16 RAM cellsare connected in such a way so that the “upper” 8 RAM cells are arrangedas two columns of four RAM cells of LUT 3210 (FIG. 39) and the “lower” 8RAM cells are arranged as two columns of four RAM cells of LUT 3212(FIG. 39).

Reference is now made to FIG. 44, which shows the layout of Metal 2,Metal 3, and Metal 4 of the eCell 3200 which is overlaying the layout ofFIG. 43. FIG. 44 shows Word Lines WL 3510 and WL 3512 (FIG. 43) forapplying the gate input signals, respectively, to the columns of 3502and 3504 of the RAM cells (FIG. 43). FIG. 44 also shows the eight pairsof the bit lines (BL and BLB) for the 16 RAM cell. For example, 2-bitlines BL and BLB, 3514 and 3516 respectively, are the 2-bit lines of thetwo RAM cells at the top of columns 3502, 3504.

Reference is now made to FIG. 45, which shows a layout of an eUnit 3520,comprising an array of 16×16 cells 3200. By flipping over the structureof the cell 3200 (FIG. 39) and placing two cells 3200 “back-to-back”, itis possible to obtain a four column RAM cell 3526. Column 3526 comprises4 Word Lines (WL) and 16×8 pairs of bit lines (BL and BLB). The wordlines and bit lines are used as a conventional 6-transistor SRAM towrite and read data into the RAM cell of LUTs.

In accordance with an embodiment of the present invention, the wordlines, WL, and the bit lines BL, BLB, may be used to generate a dualport SRAM from the RAM cell 3310 (FIG. 41) and the decoders 3312 and3313 (FIG. 41) of the cell 3200.

The eUnit 3520 comprises a column structure 3532, called a “YDECcircuit”. The YDEC circuit controls the bit lines, BL and BLB, for thedual-port SRAM. eUnit 3520 also comprises a row structure 3524 calledthe “XDEC” circuit for controlling the word lines, WL, for the dual-portRAM.

The WL, BL and BLB lines are used for a writing function in thedual-port SRAM mode. The reading function uses the decoder functions ofLUTX 3210 and of LUTY 3212, and MUX 3211 and allows the decoding of 1RAM cell out of the 16 RAM cells within the eCell 3200 of FIG. 39, whenYN 3205 is connected to M0 (3240) using jumper connector 3206

The eUnit 3520 when fully configured as a dual-port RAM provides a 4 kbit RAM structure as 256×16. Each row 3529 comprises 16 eCells 3200 andassociated with one data line for read DB-line 3254 (FIG. 39) and onedata line for write DI-line 3666 (FIG. 47). There are 16 rows 3529 inthe eUnit 3520. The XDEC 3524 has 16 repeating circuits 3600 (FIG. 46)to control the 16 columns comprising the eUnit 3520. The YDEC 3532 has16 repeating circuits each of which comprise 8 circuits 3650 (FIG. 47)to control the 16 rows comprising the eUnit 3520.

Reference is now made to FIG. 45B, which shows a ½-eCore 7000 typicallycomprising an array of 4×2 eUnits. The ½-eCore 7000 includes additionalcircuits such as a X-Decoder 7010 and a Y-Decoder 7012 which are usedfor loading the LUTs. Loading of the LUTs is done in the set-up mode,which follows every power-up and allows the operation of the eCell as alogic function. For the set-up mode, the Bit lines are driven by theY-Decoder 7012 as horizontal lines to 4 eUnits 7014A, 7014B, 7016A and7016B, located “horizontally” relative to Y-Decoder 7012, in the senseof FIG. 45B, wherein the two eUnits 7014A and 7014B are located to theleft of Y-Decoder 7012 and the two eUnits 7016A and 7016B are located tothe right of Y-Decoder 7012. The word lines are driven by the X-Decoder7012 to two eUnits as vertical lines, in the sense of FIG. 45B

FIG. 45B also shows the location of a XDEC circuit 7018 and a YDECcircuit 7020 in an eUnit 7022.

Reference is now made to FIG. 46, which shows a repeating circuit withinXDEC 3524 (FIG. 45) circuit 3600 for controlling the Word Lines, WL. TheXDEC circuit 3600 comprises a Read port decoder 3602 and a Write portdecoder 3604. Circuit 3600 is repeated 16 times to support the 16columns within eUnit 3520.

The Read port decoder 3602 controls the drive of the 4 lowestsignificant bits of read address lines by driving lines RA, RB, RC, andRD, labelled 3606, 3608, 3610 and 3612, respectively. The eUnit 3520comprises 16×16 eCells 3200 arranged as 16 columns each columncomprising 16 eCells 3200. As described hereinabove, the eCells areplaced “back-to-back” so that the 8 columns 3527 have the RAM cell onits left and the 8 columns 3528 have the RAM cell on its right. When theeUnit 3520 is configured as a dual-port RAM all the input lines of theeCell 3200, within a column 3527 or 3528, are connected in a way so asto enable the use of decoder logic within the eCell 3200 as part of thedual-port RAM read port. Thus, all the 16×A inputs 3216 (FIG. 39) andthe YA inputs 3226 are connected together to be driven by the readaddress 0-RA0–3606 (FIG. 46). Similarly, all the 16 XB input 3218 andthe 16 YB input 3228 are connected together to be driven by the readaddress 1-RA1-3608. The 16 XC1 input 3220, the 16 XC2 input 3222, the 16YC1 input 3230 and the 16 YC2 input 3232 are connected together to bedriven by the read address 2-RA2-3610. Finally, the 16 MS inputs 3262are connected together to be driven by read address 3-RA3-3612.

The motivation to segment these connections into columns is to savedrive power. Since in the read operation the XDEC 3600 selects onecolumn 3527/3528 only that column decoder circuits need to be activated.

In FIG. 46, the reference numeral 3614 labels the 8 read address linesRA4, RA5, RA6, RA7 and their inversions. The inverted read address linesare not shown in FIG. 46. The lines RA4, RA5, RA6, RA7 and theirinversions are used to select one column out of the 16 columns in theeUnit 3520 using a NAND device 3616. The NAND device 3616 is connectedto 4 out of the 8 read address lines 3614. This also enables unit 3618to provide the READ/ENABLE signal RWL on line 3620. Line 3620 isconnected to REN signals of the eCells 3200 of the particular column.This opens the 16 3-state inverters 3258 of the selected column totransfer the decoded RAM cell output to the 16 DB lines 3254 (FIG. 39).

The Write port decoder 3604 is only active when the set-up controlsignal SU (3622) is at logic “0” Otherwise, in a set-up mode, the wordlines WL0 (3624) and WL1 (3626) are logically connected to the previouseUnit word lines PWL0 (3628) and PWL1 (3630). Thus, in the set-up mode,all the word lines are controlled by the set-up control logic X-Decoder4010.

A 4-input NAND 3632 is connected to 4 of the 8 lines of the foremostsignificant write addresses and their inversions. A “0” logic isoutputted by the NAND 3632 as per the 4 most significant write addressbits as hereinabove, to select the cell column out of the 16 columns ofthe array of cells, for the write cycle. When the NAND 3632 output is“0”, either WL0 3624 or WL1 3626 become high, according to the writeport address line WA3 and its inversion WA3B.

Reference is now made to FIG. 47, which shows a repeating circuit 3650,within YDEC 3532 (FIG. 45), for providing the necessary control to thebit lines BL, BLB. Circuit 3650 is repeated 8 times for each of the 16RAWs of the eUnit 3520.

FIG. 47 shows a typical circuit for each of the 8-pairs of bit lines BL,BLB, as provided for each eCell. In the set up mode, line SU 3652 ishigh, bit lines BL 3654 and BB 3656 are connected to the bit lines PBL3658 and PBB 3660 of a previous eUnit (not shown) and are controlled bythe set up logic Y-Decoder 4012. Otherwise, in the dual-port-RAM mode,the control line 3652 is low, and for one out of 8-pairs of bit lines BL3654 and BB 3656 the control line 3663 is high. Thus, the BL 3654 isconnected through transistor 3668 to the data-input line DI 3666 and theBB line 3656 is connected to the inverted data-input line 3663 throughtransistor 3669.

Reference is now made to FIG. 48, which shows logic of the control line3663 (FIG. 47). The circuit 3670 decodes the 3 less significant writeaddress lines WA0, WA1, and WA2, to select one of the 8 pairs. For eachrow of eCells 3200, there is 8 circuits 3650 of FIG. 47. Each circuit3650 has its line 3663 connected to one of the 8 outputs, Y(0), Y(1),Y(2), Y(3), Y(4), Y(5), Y(6), and Y(7), of FIG. 47. Control line 3663 ishigh for the one of 8 circuits selected by 3670 (FIG. 48) and low forthe other seven. When control line 3663 is low then transistors 3668 and3669 are off and transistors 3661 and 3665 are on helping pulling-up thebit lines 3654 and 3656.

When bit lines BL (3407) and BLB (3410) (FIG. 42) are high then there isno write operation into the RAM cell 3320A even if the word line 3404 ishigh. This allows a proper selection of the RAM to be written into. TheRAM cells whose word line is high and bit lines are not pulled-up butrather have one logic level on its bit line BL and inverted logic levelon its BLB bit line, is performing an active write cycle. As can be seenin FIG. 45, word lines are vertical and bit lines are horizontal, whichallows the proper selection to take place.

In the set-up mode, the Y-Decoder 7012 drives one pair of bit-lines outof 2×16×8 pairs while all the other bit-lines are pulled up bytransistors 3661 and 3662 for the BL line and transistors 3665 and 3664for the BLB line. For the dual-port-RAM mode, the YDEC 3532 of theeUnit, which is customized by the top metal layer to operate in suchmode, drives one pair of bit-lines of the 8 within a RAW while all theother bit lines are pulled up by transistors 3661 and 3662 for the BLline and transistors 3665 and 3664 for the BLB line.

As shown in FIG. 47 for the circuit 3650, which has its control line3663 selected by circuit 3670 (FIG. 48), transistors 3661 and 3665 areoff and transistors 3668 and 3669 are on. In such a case the data inline 3666 drives the bit line BL 3654 while the inverted data of line3666 drives through transistor 3669 to the other bit line BLB 3656 toallow a write cycle to take place.

At each write cycle, one word line is selected by XDEC 3524 and 16 bitline BL, BLB pairs are selected by YDEC 3532 to perform a writeoperation into the 16 RAM cells selected. In some applications, it maybe preferred to have the dual-port-RAM structure with data input widthof less than 16 bits. In such a case, the top metal customization shouldprovide the disabling of the operation for some of the 16 circuits 3670within the YDEC by tying the WE line 3672 to a low logic. This disablesthe write operation to those rows.

It is appreciated that the pull-up of the bit lines is divided betweenthe two sets of transistors—the first pair of transistors 3662, 3664 andthe second pair of transistors 3661, 3665 (FIG. 47). The reason fordividing the pull-up is to support the two modes of operation. The firstmode of operation is the “set-up mode”, in which four eUnits areconnected to the same bit lines, for example in FIG. 47 line 3658 isconnected to 3654 and so forth for the four eUnits. Additionally, inFIG. 47, the bit line bar 3660 is connected to 3656 and so forth for thefour eUnits. In the second mode of operation, namely the “dual-port RAMmode”, the write cycle is performed only in a single eUnit 3520.

In the set-up mode, the pull-up is the sum of the pull-ups of the fourcircuits 3650, since in this mode, the Y-Decoder is driving thebit-lines for the 4 eUnits. By structuring the pull-up between the twosets of transistors in the circuit 3650, the pull-up may be correctlydesigned for each mode. Thus, in the set-up mode, in which the SU line3652 is high, disconnecting transistors 3662 and 3664 leaves the pull-upto the relatively weak transistors 3661 and 3665, as indicated in FIG.47. Since there are 4 pull-up circuits in parallel, the pull-up of 4such weak transistors, is still sufficient and the drive circuit of theY-Decoder 4012 can drive against the pull-up for the bit-lines that areselected for the write operation.

In the dual-port RAM mode, the SU line 3652 is low and transistors 3661and 3656 provide the pull-up. For the write operation, it is desirableto reduce the pull-up against which the write operation needs to drive.This is done by having the line 3663, namely 1 out of the 8 linesdisconnecting the second set of the pull-up transistors 3661 and 3665,while opening 3668 and 3669 to drive the data input against theremaining pull-ups. Having the data input on BL line 3654 and theinverted data input on BB line 3656 writes the data into the connectedRAM bit whose word line is high. Thus, the sizes of the transistors incircuit 3650 are therefore selected to allow both modes of operation tobe correctly controlled and operated.

The activation of the selection line is also conditional on the writesignal WE 3672.

Thus in accordance with the preferred embodiment of the presentinvention, it is possible to provide dual usage of the RAM bits. Bymetal connection, the RAM cell may be customized as a Look-Up-Table(LUT) or as a Dual-Port memory. By providing a special circuit tocontrol the word-lines and bit-lines, it is possible to allow two usesof the word lines and the bit lines in the set-up mode. Namely, to loadthe content of the LUT, and in the dual-port memory mode, to provide thewrite port. Furthermore, by utilizing the XDEC circuit, the built-indecoding circuit of the cell 3200 and the addition of a dedicated3-state inverter 3258, it is possible to provide a Read Port foroutputting the decoded RAM data.

It is also appreciated that the configuration of the eUnit 3520 could bemade to be partially a logic and partially dual-port RAM. The dual-portRAM could be cut in a rectangle shape, starting from the top left-handcorner 3522 (FIG. 45). By having proper jumper connections and pull-ups(not shown) it could be configured that only a portion on the located tothe left of XDEC is operative together with a portion located near tothe top of the YDEC.

In accordance with another preferred embodiment of the presentinvention, an improvement in running a CK-tree is disclosed hereinbelow.

Conventionally, a well-balanced CK-tree is to pass clock signals to allF/Fs. Each F/F includes an inverter to create the CKB signals asrequired. However, this conventional technique is prone to use asignificant amount of power, create RF noise as the clock frequency isincreased and also to produce spikes on the power lines.

Taking advantage of the eCell 3200 structure, that provides the F/F aspart of the eCell at fixed location, the CK-tree may be predesigned andincluded in the basic pattern of the cell. Thus, in accordance with apreferred embodiment of the present invention, CK-trees are produced forthe CK signal and for the CKB signal.

Reference is now made to FIG. 49, which shows eight eUnits 3770 arrangedin a 2×4 array 3772, constructed and operative in accordance withanother preferred embodiment of the present invention. The eight eUnits3770 as arranged in a 2×4 array 3772 is termed in the presentspecification and claims as “½-eCore”. The ½-eCore 3772 includes an8-eUnit cells 3770, each eUnit cell 3770 comprising a 16×16 array ofcells 3200. The ½- -eCore 3772 also comprises a built-in clock H-clocktree 3774. The clock tree 3774 feeds a secondary H-tree 3776. The½-eCore 3772 also includes a drive 3778 to drive the clock tree 3774. Aclock feedback 3776 is the CK feedback signal, and is provided in orderto enable cancelling insertion delay by using a PLL.

The secondary H-trees 3776 feed each eUnit 3770 with a clock signal sothat all eUnits within the same ½-eCore 3572 receive the clock signal atthe same time with minimum skew.

Reference is now made to FIG. 50, which shows a typical clock unit 3780located within the eUnit 3770. The clock unit 3780 comprises driverinverter 3786 for generating the CKB signal, by inverting the CK signal3788 and then to drive driver circuits 3782 and 3784 for the CK and CKBsignals, respectively, which are applied to each of the 16 cell columnscomprising the eUnit 3770 (FIG. 45).

Using both the CK and CKB signals, the CK noise cancels the CKB noiseand also reduces the spikes on the power lines. Furthermore, powerconsumption is also reduced by decreasing the number of inverters usedfor producing CKB signals

Reference is now made to FIG. 51, which shows a circuit 3790 forproviding reduced power and supply noise reduction. The circuit 3790comprises a transistor 3792, which is connected between CK and CKB lines3794 and 3796, respectively, and a timing line 3798 (CKP) forswitching-on the transistor 3792. By turning on the transistor 3792 atthe correct time and for the correct duration, the CK and CKB lines areshorted, thus allowing the exchange of electric charges, until thevoltages on the CK and CKB lines are equal. Once the voltages on the CKand the CKB lines are equalized (3798), the transistor 3792 isturned-off and the CK and CKB drivers 3782 and 3784, respectively,charge the lines to their new levels, as shown in FIG. 52.

Reference is now made to FIG. 53, which shows a typical circuit 3800useful for generating the timing signal 3798 for turning-on andturning-off the transistor 3792 (FIG. 51), operated and constructed inaccordance with a preferred embodiment of the present invention. Theinput clock signal 3802 is fed, in parallel, to a clock driver circuit3803 and to the CKP timing generator circuit 3800. The timing generatorcircuit 3800 comprises a delay chain section 3804, a XOR circuit 3806and a final driver stage 3808. The delay circuit 3804 is designed toprovide the required pulse width of the CKP signal 3798. The XOR circuit3806 generates a pulse 3810 by XORing the input CLK signal 3802 with adelayed signal 3812, produced by delay circuit 3804. The signal 3810 isa pulse-type signal, which provides a pulse for each transition (goingfrom high to low or from low to high) of the clock. The drive circuit3808 introduces an additional delay to the pulse 3810 in order toprovide the correct timing for the signal 3798 and strength to correctlydrive the transistor 3792.

In FIG. 53, clock line CK1 3811 is driving the CLK line 3788 (FIG. 50).

Reference is now made to FIG. 54, which shows a flowchart 3900illustrating a method for using the code “Design Compiler” forprogramming the cell 3200 (FIG. 39) to perform more than 32,000different logic functions, in accordance with a preferred embodiment ofthe present invention. “Design Compiler” is available from SynopsysInc., 700 E. Middlefield, Mountain View, Calif., USA.

The first step 3905 is to build a library, eLIB, of typically less than1,000 logic functions. Then using eLIB and the synthesis tool “DesignCompiler”, synthesize a High-Level design (RTL) to gate level (step3910). The logic level of the synthesis process is termed in the presentspecification and claims “e-netlist”.

Step 3920 comprises mapping the function, within the e-netlist, into thelogic element of the cell 3200 to perform the required logic function;this mapping process is termed in the present specification and claimsas “e-mapping”.

In the next step 3930, the logic elements are clustered into cells,termed “eCell-netlist”. Step 3930 is termed in the present specificationand claims as “e-packing”.

Reference is now made to FIG. 55, which presents typical steps useful inimplementing step 3905 for constructing the library eLIB, in accordancewith a preferred embodiment of the present invention. Step 3905comprises the following substeps:

Step 3940: In this step, the F/F function is constructed including thefunctions DFF; Enabling DFF; and Synchromatic Reset DFF.

DFF is the cell 3244 (FIG. 39) known in the art as Dflip/Flop. Using themultiplexer 3211, the jumpers of the eCell 3200 could be configured toprovide additional Flip/Flop functions.

Enabled Dflip/Flop is constructed by connecting the QN output of 3244 toM0 3240 of the multiplexer 3211 using jumper 3204 or 3202 (FIG. 39). Insuch a case, the MS input 3262 becomes the enable control line of theenabled F/F and as long as the MS 3262 is low, the F/F maintains itscurrent data. In another configuration, VDD could be connected to the M0input of the multiplexer 3211 by jumper 3206 or 3208. In such aconfiguration, the MS input 3262 becomes the synchronic reset signal.This means that when the input MS 3262 is low, the F/F 3244 is reset onthe next clock.

Step 3950: In this step the inverter function is constructed andincludes implementing the functions 6× inverter 3260 (FIG. 39) and 8×inverter 3269 (FIG. 39).

Step 3960: In this step, the 2-input function is constructed andincludes the step of implementing the 16 logic functions, which can beimplemented by LUT-3 when it is reduced to LUT-2.

Step 3970: In this step, the 3-input function is constructed andincludes the step of implementing the 256 functions, which may beimplemented by LUT-3.

Step 3980: In this step, the 4-input function in constructed andincludes the step of implementing the 256 logic functions which may beimplemented by LUT-3 with a NAND-2 on one of its input lines.

The construction of eLIB (step 3905) provides a library with typicallyless than 1,000 logic functions and therefore allows the use of thesynthesis tool “Design Compiler”.

In step 3920, the output of the synthesis tool, namely the e-netlist ismapped and packed into the cell 3200 and is termed in the presentspecification and claims as “eCell-netlist”.

In accordance with a preferred embodiment of the present invention,configuring the multiplexer MUX 3211 (FIG. 39) to many 2-input functionsallow the mapping of the 2-input function into MUX 3211. Additionally,in accordance with a preferred embodiment of the present invention,certain subset 3-input function which are in step 3970 may also bemapped into MUX 3211.

In accordance the preferred embodiment of the present invention, 2-inputfunctions such as AND and NAND functions may also be mapped into theNAND device located in the input lines of LUT 3212 (FIG. 39).

In accordance with yet another preferred embodiment of the presentinvention, the 2-step process described hereinabove may also be used toimprove performance of a logic design. For example, it is known in theart that a multiplexer such as MUX 3211 (FIG. 39) typically has a fasterresponse time than a LUT unit, such as LUT 3210 and LUT 3212 of FIG. 39.By using the mapping method as described hereinabove, an improved designperformance may be achieved in addition to improving the design of thesilicon density.

In order to improve performance, the mapping step should first givepriority to map the logic functions, which are on the critical path toMUX 3211. Reducing the response time of the critical path, is generallyrelated to improving the performance of the design.

In accordance with a further embodiment of the present invention, a RAMcell, may be replaced by a non-volatile ferro-electric or ferro-magneticmemory cell.

An advantage of using ferro-electric and ferro-magnetic memory cells isthat these cells do not lose data when power is switched-off. Anadditional advantage of ferro-electric and ferro-magnetic memory cellsis that these cells are typically smaller than a RAM cell unit. Thus,ferro-electric and ferro-magnetic memory cells are more economical byrequiring smaller quantities of silicon. A smaller cell provides fasterLUT performance and consumes less power. U.S. Pat. No. 5,565,695, thedisclosure of which is incorporated by reference, teaches the use of amagnetic spin transistor for a non-volatile memory

In accordance with yet another preferred embodiment of the presentinvention, a memory structure may be provided that is laserprogrammable. Such methods are known in the art and described in U.S.Pat. No. 5,940,727, entitled “Technique For Producing InterconnectingConductive Links”, issued Aug. 17, 1999, inventor Joseph B. Bernstein,and assigned to Massachusetts Institute of Technology, Cambridge, Mass.,USA, the disclosure of which is incorporated by reference. With such anapproach high-density RAM cells may be manufactured with a goodmanufacturing turnaround time.

In accordance with yet another preferred embodiment of the presentinvention, the RAM cell 3320A (FIG. 42) may be replaced with a “fixedconnection” device, by using “via programming” for creating a connectionbetween 2 overlaying metal layers, such as Metal 3 and Metal 4 layers.In such a case, although the LUT device cannot be changed orreprogrammed, however, by using the “fixed connection” device there is asignificant saving in silicon area.

Reference is now made to FIG. 56A, which shows a typical layout of sucha “fixed connection” device which is designed to replace the 8 RAM cells3320A–320H of FIG. 41. In FIG. 56A, the metal strips 3988 and 3989 areoverlayed by the strips 3990A–990H. The metal strip 3988 is preferablyconnected to the VDD line and the metal strip 3989 is preferablyconnected to the VSS line. The strips 3990A–990H are identified with theoutput lines R(0) . . . R(7) from the 8 RAM cells 3320A–320H (line 3412in FIG. 42).

In operation of a specific logic configuration, the programming of theLUT is performed by connecting the via 3992A to the VDD line by means ofthe metal strip 3988 and the via 3992B to the VSS line by means of themetal strip 3989, respectively, as described hereinbelow. Inpreparation, such a task is preferably undertaken by using a mask withthe required pattern.

Reference is now made to FIG. 56B, which shows the requiredconfiguration for low level logic. In the layout shown in FIG. 56B, thevia 3992A connects between the relevant line from R(0) . . . R(7) withthe VSS line.

Reference is further made to FIG. 56C, which shows the requiredconfiguration for high level logic. In the layout shown in FIG. 56C, thevia 3992B connects between the relevant line from R(0) . . . R(7) withthe VDD line.

Reference is now made to FIGS. 57A and 57B, which show a simplifiedillustration of a typical logic array comprising a plurality ofidentical logic array modules in accordance with a preferred embodimentof the present invention. FIGS. 57A and 57B show a typical applicationspecific integrated circuit (ASIC) 4010 which includes therewithin on asingle silicon substrate a number of components, such as a data memory4012, a digital signal processor (DSP) 4014, an instruction memory 4016,reused logic 4018, a ROM 4020, a RAM 4022, and a CPU 4024. In accordancewith a preferred embodiment of the present invention, also includeslogic formed of a plurality of logic array modules 4030, which in thisexample, appear in a number of different forms.

It is a particular feature of the present invention that the logic arraymodules 4030, also termed modular logic array units, are arranged in adesired mutual arrangement without the requirement of compilation. Thelogic array modules 4030 are preferably physically arranged with respectto each other to define a desired aspect ratio.

In accordance with a preferred embodiment of the present invention, thelogic of ASIC 4010 is preferably produced by using a data file for amodular logic array which comprises at least a reference to a pluralityof identical modular data files, each corresponding to a logic arrayunit and data determining the physical arrangement of the logic unitswith respect to each other.

In the illustrated embodiment of FIGS. 57A and 57B, modules 4030 having3 different configurations are provided. It is appreciated that one orany suitable number of different configurations of modules may beemployed in any application.

In accordance with a preferred embodiment of the present invention theborder between each modular logic array unit and its neighbor may beidentified by at least one row 4040 of stitches 4042. In the illustratedembodiment of FIGS. 57A and 57B, stitches 4042 are embodied in removableconductive strips 4044 formed in a relatively high metal layer, such asa top metal layer. The strips 4044 are preferably connected by vias 4048to strips 4040 in a relatively lower metal layer, such as a next-to-topmetal layer, thereby to removably bridge gaps 4042 therebetween.

Preferably each logic array module 4030 comprises between 10,000 and200,000 gates and has an area of between 0.5 square millimeter and 6square millimeters.

Reference is now made to FIGS. 58A, 58B & 58C which illustrate threetypical configurations of logic array modules in accordance with apreferred embodiment of the present invention. The module of FIG. 58Ahas a generally square configuration and typical dimensions of 2 mm×2mm. The module of FIG. 58B has a generally rectangular configuration andtypical dimensions of 4 mm×1 mm. The module of FIG. 58C has a generallyrectangular configuration and typical dimensions of 1 mm×4 mm.

Reference is now made to FIGS. 59A and 59B, which are simplifiedillustrations of various different arrangements of identical logic arraymodules useful in accordance with the present invention. FIG. 59Aillustrates two square modules 4050 arranged with their scan inputs andscan outputs in a parallel arrangement. FIG. 59B shows two squaremodules 4050, which may be identical to the modules of FIG. 59A,arranged with their scan inputs and scan outputs in a seriesarrangement.

FIGS. 60A and 60B are simplified illustrations of logic array modulestiled together in two different arrangements providing substantiallyrectangular arrays with different aspect ratios.

Reference is now made to FIG. 61, which shows a programmable IntegratedCircuit (IC) device 5010 constructed and operative according to apreferred embodiment of the present invention. The integrated circuitdevice 5010 may be a stand-alone device or may, alternatively, beintegrated into a larger device. In such a case, the device mayconstitute a programmable portion of a system on a chip.

The underlying architecture of the integrated circuit device 5010 iscomprised of an array of LUT programmable blocks 5012 connected by fixedmetal routing or by programmable routing. By controlling the content ofthe LUT of individual blocks 5012 of the device 5010 it is possible toidentify and isolate both logical and circuit faults in circuitsconstructed from LUTs, while the device 5010 is operating in afunctional working mode.

Reference is now made to FIG. 62A, which is a simplified representationof the layout of the input/output connections of a conventional 2-bitLUT device 5020 constructed and operative according to a preferredembodiment of the present invention. It is appreciated that the LUTdevice 5020 may typically be an individual block 5012 in the array ofthe device 5010 of FIG. 61.

In FIG. 62A it is seen that the LUT 5020 comprises two input ports 5022and 5024, and an output port 5026. FIG. 62B shows the typical truthtable 5027 for the LUT device illustrated in FIG. 62A. “A” and “B”represent the binary input signals to LUT unit 5020 and “C” representsthe binary output values, b₁, b₂, b₃, and b₄, from the unit 5020. Inaccordance with a preferred embodiment of the present invention, byreprogramming the unit 5020, it is possible to provide controllabilityas required for debugging.

Using NAND as an exemplary gate, the output values are given by thetruth table 5028 as listed in FIG. 62C. After reprogramming, to providea controlling value of “0”, the output values are given by the truthtable 5029, as shown in FIG. 62D.

Thus, in accordance with a preferred embodiment of the presentinvention, by isolating a particular LUT in a block, reprogramming andnoting the input values to the device, and recording the output values,the designer is able to resolve the error in the design.

Reference is now made to FIG. 63A, which shows a circuit 5032, which maybe a portion of the array 5010 (FIG. 61), and comprising 4 LUT logicunits 5034 (I), 5036 (II), 5038 (III) and 5040 (IV). The units 5034 and5036 include input ports 5042 and 5044, and 5046 and 5048, respectively.The output signals from the device 5032 are outputted from output ports5056 and 5058, respectively.

FIG. 63B is a schematic drawing of the device of FIG. 63A.

In normal operation, each of the 4 LUTs, comprising the device 5032,produce outputs as summarized in the truth table 5048 of FIG. 63C.

If for example, in the debugging process it is desired to control theoutput of the LUT unit 5034 of the device 5032, the LUT 5034 may bereprogrammed and the output of LUT 5034 forced to “0”, as shown by thetruth table 5050 in FIG. 64A. The truth table 5052 presents theunchanged truth table of the individual LUTs 5036, 5038 and 5040 (FIG.64A). An equivalent schematic drawing 5054 is shown in FIG. 64B in whichthe LUT 5034 is substituted by a “0”. Thus, in accordance with apreferred embodiment of the present invention, the output from a LUTdevice may be controlled to give a predicted result, as is shown in thepresent case for LUT 5034.

Similarly, in accordance with a preferred embodiment of the presentinvention, it is also possible to reprogram the inputs to LUT 5034 toforce the output to “1”, as shown in truth table 5060 of FIG. 65A. Thetruth table 5062, which presents the unchanged truth table of theindividual LUTs 5036, 5038 and 5040, is also shown. An equivalentschematic 5064 is shown in FIG. 65B, in which the LUT 5034 is nowsubstituted by a “1”. As previously, the output from device 5032 iscontrollable and dependent on LUT 4034.

As described above, a substitution of truth tables in a LUT can make theLUT appear to have a fixed or “stuck-at” value on its inputs or output.By successively selecting both “stuck-at” values for every input andoutput, and executing the customized function's test vectors, averification of the test vectors' fault coverage can be obtained.

Reference is now made to FIG. 66A, which shows truth tables 5072 and5074. FIG. 66A, shows a truth table 5072 for an AND gate, and a truthtable 5074 for a NAND gate. Thus, if LUT 5034 is reprogrammed with truthtable 5072, and the remaining units 5036, 5038 and 5040 are unchanged, alogic circuit 5076, as shown in FIG. 66B, may be achieved. In FIG. 66B,the NAND gate 5034 is changed from a NAND to an AND gate. A LUT can thusbe reprogrammed to give an inverted result of the function of LUT 5034,as may be required in the debugging process.

Reference is now made to FIG. 67A, which presents truth tables 5078 and5080. The truth table 5078 is that of a NAND gate in which one of itsinputs is tied to logic “1”, or simply an inversion of the “B” input.Thus, if LUT 5034 is reprogrammed with truth table 5078, and the LUTunits 5036, 5038 and 5040 are unchanged, a logic circuit 5082 (FIG. 67B)is achieved. Thus, a further type of controllability is obtained whichmay be required in a debugging process. This allows the effect of signal5044 to be observed while signal 5042 is disconnected.

In a debugging operation, a user identifies the LUT unit to reprogram,by modifying a reference port of an object in the high-level datadescription. Once the port is identified, the user is offered a choiceof changes to select, and on selection, an appropriate change is made inthe machine readable data file which programs the device. Themachine-readable file is downloaded to the integrated circuit and thedesired change is effected. The debugging process is carried out bymonitoring the result of the chosen unit.

Reference is now made to FIG. 68, which illustrates in very generalterms a preferred method of semiconductor design and fabrication inaccordance with a preferred embodiment of the present invention.

As seen in FIG. 68, in accordance with a preferred embodiment of thepresent invention, three entities participate in the semiconductordesign and fabrication: the customer, a core provider's web site or coreprovider's portal and a foundry. In a preferred embodiment, the coreprovider may or may not be the actual developer of the core.

The core provider's web site or a portal providing access to a pluralityof web sites of various core providers provides a searchable databasedescribing various cores which are commercially available for use bydesigners as well as core data suitable for download. In accordance witha preferred embodiment of the present invention, the core data bearsembedded identification indicia, which enables the presence of the coredata to be readily identified downstream when the core is embedded in achip design such as a system on a chip design.

The identification indicia may also include version identificationindicia which enables updated versions of the core data to be readilycataloged and identified to ensure that the most updated version isincorporated in the chip design.

The cores which are provided via the core provider's web site may bestatic cores, such as those commercially available from ARM, Ltd. oralternatively customizable or customizable cores, such as thosecommercially available from eASIC of San Jose, Calif., USA.

In accordance with a preferred embodiment of the present invention, thecustomer after having defined his requirements dials up to the coreprovider's web site either directly or via a core providers' portal,identifies a core which appears to fit his requirements and downloadsthe core data, bearing the embedded identification indicia. It is aparticular feature of the present invention that the customer worksinteractively with the core provider's web site in the core selectionprocess, thus greatly increasing the efficiency of the core selectionintegration process.

Once the customer has received the core data, he integrates it,including the embedded identification indicia into a chip design, suchas a system on a chip design. After carrying out suitable checks, thecustomer transfers the system on chip data, including the embeddedidentification indicia, to a foundry.

The foundry processes the system on chip data for integrated circuitfabrication and employs the embedded identification indicia to determinethe existence and amount of royalties owed to the core providers. Usingthis information, the foundry provides required cost estimates for thecustomer. Once these are approved and payment of royalties to the coreproviders is arranged, fabrication of Ics based on the chip design iscarried out.

Reference is now made to FIGS. 69A and 69B, which are together aflowchart illustrating a preferred method of semiconductor design andfabrication in accordance with a preferred embodiment of the presentinvention.

As seen in greater detail in FIGS. 69A and 69B, prior to interactionwith the core provider's web site, the customer completes an overallsystem design and a block level design in a conventional manner. Thecustomer also determines his core requirements which include performancerequirements and whether the core may be static or is required to becustomizable and/or programmable.

Once the customer has determined his core requirements he preferablyestablishes communication with a web site of one or more core providers,preferably via the Internet. Using established menus and interactivesearching and selection techniques, the customer selects requireparameters of the cores, such as the fab type, for example TSMC and UMC,and the fab process, such as 0.25 micron or 0.18 micron.

The customer then selects an available core which appears to meet thecustomer's requirements and confirms that the selected core meets thecustomer's earlier defined block level design requirements. Thisconfirmation is preferably carried out in an interactive manner via theInternet.

If there is an incompatibility between the block level designrequirements and the selected core characteristics, the customerpreferably revises the block level design to eliminate theincompatibility. This process continues until no incompatibility exists.At that stage the physical data, using industry standard format such asGDS-II, of the selected core is downloaded by the customer, preferablyvia the Internet.

As noted above, in accordance with a preferred embodiment of the presentinvention, the core data bears embedded identification indicia, whichenables the presence of the core data to be readily identifieddownstream when the core is embedded in a chip design such as a systemon a chip design.

Upon receiving the downloaded core data, the customer integrates it,including the embedded identification indicia, into a chip design, suchas a system on a chip design. The customer then checks that the core, asintegrated into the chip design, meets the system requirements earlierestablished by the customer.

If the system requirements are not met, the system design is revised,possibly interactively with the entire core process, preferably via theInternet. Once any necessary revisions in the system design have beenmade and it is determined that the core as integrated fulfills thesystem requirements, the customer transfers the system on chip data,including the embedded identification indicia, to a foundry. Thistransfer may also take place via the Internet.

Upon receiving the chip data from the customer, the foundry confirmsthat the chip data is ready for production. If the data is, for anyreason, not ready for production, the foundry interacts with thecustomer to resolve whatever problems exist. This may require that thecustomer revise all of its design steps described hereinabove includinginteraction with the core provider via the Internet.

Once all producibility problems have been resolved, the foundryprocesses the system on chip data for integrated circuit fabrication andemploys the embedded identification indicia to determine the existenceand amount of royalties owed to the core providers. In accordance with apreferred embodiment of the present invention, the foundry also employsthe embedded identification indicia to ensure that the most updatedversions of the core data and chip design data are being employed.

Using the embedded indicia and other information, the foundry providesrequired cost estimates for the customer. These include NRE costs, whichmay include NRE payments to core providers, as well as anticipated perunit costs which include per unit royalties to core providers. Once thecosts are approved and payment of royalties to the core providers isarranged, fabrication of Ics based on the chip design is carried out.

In another preferred embodiment of the invention, the NRE and/or royaltypayments may be made directly to the core developer if the coredeveloper is not the core provider, or the NRE and/or royalty paymentsmay be made directly from the foundry, as opposed to the customer.

In another preferred embodiment of the invention, a fourth entity, theMask Shop, may confirm the chip data is ready for production and employthe embedded identification indicia to determine the existence andamount of royalties owed to the core providers.

In yet another preferred embodiment of the invention, the embeddedidentification indicia may include encrypted data, which identifies thesize, type and revision of the customizable core. One such method wouldbe to add a mask layer, which contains data necessary to the fabricationof the part, as well as encrypted data for identification and sizing ofthe core. The necessary fabrication data is extracted and used bycombining this layer with other appropriate layers when creating themasks for fabrication. The same process is followed to extract theidentification and sizing information, only the choice of operations andmask layers changes. The choice of mask layers and the actual operationsare contained within a proprietary process that is provided to thefoundry or mask shop by the core developer.

In another preferred embodiment of the invention, the chip data providedby the customer is not sufficient to create the core. Rather, theembedded identification indicia contain references to library data thatis provided to the foundry or mask shop by the core developer. Theproprietary process would include addition of the appropriate librarydata, as defined by the embedded identification indicia, into thecustomer's chip data. In this embodiment the most updated version of thecore data may be provided to the foundry or mask shop, by the coredeveloper, within the library data. By including the appropriate librarydata, the most updated version of core data is thereby employed. In thisembodiment, the core provider provides the customer with sufficientinformation to design and create the chip data, without providingsufficient information to fabricate the core.

Reference is now made to FIG. 70 which presents a simplified flowchartshowing the use of a Virtual ASIC entity, by a customer, to provide acustom-effective design of an S.O.C.

It is seen in FIG. 70, that various S.O.C. providers forward theirprogrammable and/or customizable S.O.C. options to the Virtual ASICentity. Based on the acquired data, the Virtual ASIC entity builds aS.O.C. data bank or library, which also includes the general data forthe programmable and customizable portions of each S.O.C. Each entryinto the data bank includes an identification code of the various coresprovided with each S.O.C. Additionally, the data bank includes a codesystem for identifying the S.O.C. provider who have given permission todisclose the data, and make available the tooling of the specific S.O.C.

The Virtual ASIC entity also provides a cost estimate for the use of thevarious data options and elements. These cost estimates also include thecost of the wafer and the various cores which are part of the S.O.C.

A customer who wishes to use the data bank so as to integrate theavailable data into his particular design, for example so as to save ontooling costs, searches the data bank and reviews the various S.O.C.options available from the Virtual ASIC data bank which meet his designrequirements.

The customer decides on the particular design available from the databank, which closely as possible meets his technical requirements. Thecustomer then finalizes his design which includes both programmable andcustomizable portions.

After confirming that the new S.O.C. design meets the technicalrequirements, the customer requests a cost estimate for the use of therequired data and tooling, typically taking into consideration the costsof various additional factors, such as the cost of the wafer and thecores which form part of the proposed S.O.C., the cost of integratingthe design into the S.O.C., and the cost of programming and/or thecustomization service required.

Additionally, the customer may also perform a business review with theVirtual ASIC entity, as to the turn around time of the development phaseand NRE and the services costs required.

Once the customer is satisfied with the budgetary considerations, heplaces an order with the Virtual ASIC to provide the required data andrelease of the chosen S.O.C. tooling.

The foundry processes the silicon, as required, and delivers the chip tothe Virtual ASIC for transfer to the customer.

As described hereinabove with reference to the cell array device of FIG.23, after customization, the cell array includes a total of seven metallayers, identified as M1–M7, the top metal layer being identified aslayer M7. In deep sub-micron processes it is preferable to have the topmetal layer thicker than the lower metal layers. One advantage of athick upper layer is to allow good bonding packaging process, as isknown in the art. Therefore, the top metal layer (M7) typicallycomprises a coarser pitch than the lower metal layers (M1–M6). Forexample, for a “0.15-micron process”, for the M2 to M6 metal layers, thepitch is about 0.48 micron. However, for the M7 metal layer, the pitchis about 0.90 micron.

In order to include more custom routing resources in the cell array, itis advantageous to use a metal layer with a fine pitch for thecustomization layer. Thus, in accordance with a preferred embodiment ofthe present invention, the via layer connecting between two layers,which has typically a fine pitch, is used as the custom layer. Thecoarse pitch layers, such as the M7 layer, are used as part of the longtrack layers.

Preferably, the M5M6 via layer, being of finer pitch, is used as thecustomization layer, the M5, M6 metal layers are used for long and shortrouting layers, respectively, and the M7 layer is used for long trackrouting.

It is appreciated that the time-to-market customization of the M5M6 vialayer of the present embodiment of the invention, typically takes longerthan the customization of the M6M7 via layer of the previous embodimentsof the present invention described hereinabove However, the highercircuit density resulting from the higher pitch of the M5M6 layer makesthe present embodiment commercially very attractive.

Reference is now made to FIG. 71A, which is a schematic illustration ofinterconnection structure 9000 of the 4 upper layers M4, M5, M6 and M7,prior to customization, constructed and operative in accordance with apreferred embodiment of the present invention. The structure of FIG. 71Ais similar to the one in FIG. 23 but is modified in such a way so as toprovide customization of the M5M6 via and the M6 layer.

In accordance with a preferred embodiment of the present invention, theinterconnection structure 9000 comprises a M4 metal layer for longtracks in the East-West direction and a M5 layer comprising short stripsfor local interconnections in the North-South direction. A M5M6 vialayer is the custom layer. The M6 layer is preferably used for shortlocal interconnection strips in the West-East direction. Additionally oralternatively, the M6 layer may be a custom layer or a generic layer.

In addition, the M6 layer is used for short interconnections between thelong North-South strips of M7 and to provide short interconnections, asdescribed hereinbelow.

As shown in FIG. 71A, the interconnection structure 9000 comprises a M4layer providing long tracks 9002 in the East-West direction. The longtracks 9002 comprise parallel evenly spaced bands of metal strips 9004.The strips 9004 typically extend across pairs 9006 of short strips 9008of M5 layer and are connected by means of a M4M5 via 9010 to the shortstrips 9008. The pairs 9006 provide connections to the long routingconductors 9004 in the M4 layer, in the East-West directions.

It is noted that adjacent ones of strips 9004 begin and end at strips9008 of different members of the pairs 9006, such that each pair 9006 ofstrips 9008 is connected to strips 9004 extending along a differentaxis. It is appreciated that each strip 9008 is preferably connected toonly a single strip 9004.

FIG. 71A also shows that the M5 layer comprises multiple spaced bands ofparallel evenly spaced metal strips 9014, in the North-South direction.

The interconnection structure 9000 also comprises multiple bands ofstepped M7 metal strips extending generally in the North-Southdirection. FIG. 71A shows a single band 9032 of parallel stepped strips9028.

Reference is now made to FIG. 71B, which shows in more detail theperiodic connection of the North-South long tracks 9028 in the M7 layerand the North-South short bar 9015 in the MS layer. TheWest-most/South-most end of stepped strip 9028 is connected to a M5 bar9015 by means of the short M6 strip 9024. A M6M7 via 9036 providesconnections between the M7 strips 9028 to short M6 strip 9024 and a M5M6via 9034 connects between the M6 strip 9024 and the short M5 bar 9015.

The South-most end of the short M5 bar 9015 is connected to theEast-most/North-most M7 layer step strip 9028 by means of a M5M6 via9038. A M6M7 via 9040 is located above the M5M6 via 9038.

It is appreciated that the short M5 strips 9015 provide the connectionsto the short interconnection strips. The M5M6 vias 9034 and 9038, whichare located at the respective ends of the M5 strip 9015, provide themeans by which the M5 connections continue in the North or Southdirections.

It is also appreciated that although FIGS. 71A and 71B show theconnections of a single band 9032, the 9000 pattern is repeated amultiplicity of times in both the East-West direction and in theNorth-South direction.

It is further appreciated that the number and lengths of the M7 stepstrips 9028, in a particular band 9032, may be modified and adjusted inorder to fulfill the various implementations of the interconnectionstructure 9000.

Reference is now made to FIG. 72, which provides an example of a customrouting, utilizing the pattern of FIG. 71A. In this preferred embodimentof the present invention, the customized layers used in FIGS. 72, arethe M5M6 via and the M6 layers.

FIG. 72 shows an example of connecting long tracks in M4 layer to longtracks in M7 by using the custom layers M5M6 and M6. A M4 long strip9052 is connected by a M4M5 via 9053 to a M5 strip 9054 and the M5 strip9051 is connected by means of a M5M6 via 9055 to a M6 strip 9054. The M6strip 9054 connects by means of a M5M6 via 9057 to a M5 strip 9056. Byusing, a M6 bridging strip 9058 and M5M6 via 9059, M5 strip 9060 isconnected to M5 strip 9056.

A M6 strip 9062, in the East-West direction, is connected to the M5strip 9060 by means of a M5M6 via 9064. A M5M6 via 9066 connects betweenthe M6 strip 9062 and the M5 short bar 9066. The short M5 bar 9066 isconnected to a short M6 strip 9080 by a M5M6 via 9067. The M6 shortstrip 9080 is connected to a M7 stepped strip 9082 by means of a M6M7via 9083. Thus, by connecting to the short bar 9066 and placing via 9067the connection was made to the M7 long strips in the North-Southdirection.

Another example for connecting a M4 long strip to a M7 long strip is byusing a M6 strip 9072. A M4 strip 9068 is connected by a M4M5 via 9069to M5 strip 9074. The M5 strip 9074 is connected by ViaM5M6 9075 to theM6 strip 9072 and the M6 strip 9072 is connected by M5M6 via 9070 to aM5 short bar 9076. The M5 short bar 9076 is connected by M5M6 via 9077to M6 short strip 9078. The M6 strip 9078 is connected to a M7 longstepped strip 9079 by means of a M6M7 via, located above the M5M6 via9077.

There are many ways to customize interconnections utilizing the patternas described hereinabove in accordance with this preferred embodiment ofthe present invention. The M4 strips are used for the long routing inthe West-East direction and each M4 strip is connected to the shortinterconnection strips. Each M4 strip is connected once to every threeeCells, as described hereinabove with reference to FIG. 17. The M7 stripis used for long routing in the North-South direction and each M7 stripis connected to the short interconnection strips. Each M7 strip isconnected once to every four eCells, as described hereinabove withreference to FIG. 71A. The M5 strip is used for short routing in theNorth-South direction and each M5 layer typically comprises equal sizeshort strips arranged in parallel bands. Preferably, the long M5 stripcovers one eCell. Additionally, the M5 strip includes a connecting stripto the M4 long strip, such as the M5 strips 9006 in FIG. 71A. The M5strip also includes the short bar, (strip 9015 in FIG. 71A), forconnecting to the M7 long strip, such as the M7 strip 9028 (FIG. 71A).The M6 strips are typically short strips in the direction West-East. TheM6 strip also includes small bridges for connecting short M5 strips inthe North-South direction, such as the M6 strip 9058 (FIG. 72). The M6further includes short strips 9024 in FIGS. 71A and 71B, which connectbetween the M7 stepped strips 9028 and the M5short bar 9015.

Alternatively, it is appreciated that in order to further reduce thecost of customization to a single custom mask, the M6 layer may be usedas a generic layer. In such a case, the M5M6 via layer is the onlycustomization layer and the M6 strip typically comprises a parallel bandof short strip in the East-West direction and includes short bridges forconnecting the M5 strips, which run in the North-South direction.Additionally, short bridges are preferably included in the M5 layer soas to allow the continuation of the M6 strips in the West-Eastdirection, such as described hereinabove with respect FIGS. 27, 28 and29.

Using a via layer as the customization layer may be very attractive froma commercial point-of-view. As is known in the art, the via layer isused for transferring signals between metal layers. Therefore, unlikethe metal layers, the via layers are preferably very low in patternedarea and typically use only one polygon fix in size and shape. Thus,Direct E-Beam writing technology is suitable for fast-low costcustomization.

Direct E-Beam writing is a well-known technology and conventionally usedfor R&D purposes; Direct E-Beam writing is too time-consuming forcommercial use. However, in accordance with the preferred embodiment ofthe present invention, customizing a via layer in a Cell-Array by usingDirect E-Beam technology is a very effective method for utilizing awell-known technology. Using this familiar technology typically shortenstime-to-market and allows wafer sharing by having many different designssharing one wafer. This technology will also reduce the required NREcost for prototypes.

Reference is now made to FIG. 73, which illustrates a single routingcell unit, comprising M4 and M5 layers and a M4M5 via, in accordancewith the preferred embodiment of the present invention. It isappreciated that the single routing cell unit illustrated in FIG. 73 isdrawn approximately to scale.

Reference is now made to FIG. 74, which illustrates a single routingcell unit, comprising M5 and M6 layers, in accordance with the preferredembodiment of the present invention. It is appreciated that the singlerouting cell unit illustrated in FIG. 74 is drawn approximately toscale.

Reference is now made to FIG. 75, which illustrates a single routingcell unit, comprising M6 and M7 layers and a M6M7 via, in accordancewith the preferred embodiment of the present invention. It isappreciated that the single routing cell unit illustrated in FIG. 75 isdrawn approximately to scale.

Reference is now made to FIG. 76, which illustrates a unit, comprisingM4 and M5 layers and a M4M5 via of a 2×2 cell matrix, in accordance witha preferred embodiment of the present invention. It is appreciated thatthe unit illustrated in FIG. 76 is drawn approximately to scale.

Reference is now made to FIG. 77 illustrates a unit, comprising M5 andM6 layers of a 2×2 cell matrix, in accordance with a preferredembodiment of the present invention. It is appreciated that the unitillustrated in FIG. 77 is drawn approximately to scale.

Reference is now made to FIG. 78 illustrates a unit, comprising M6 andM7 layers and a M6M7 via of a 2×2 cell matrix, in accordance with apreferred embodiment of the present invention. It is appreciated thatthe unit illustrated in FIG. 78 is drawn approximately to scale.

It will be appreciated by persons skilled in the art that the presentinvention is not limited by what has been particularly shown anddescribed hereinabove. Rather the scope of the present inventionincludes both combinations and subcombinations of various featuresdescribed hereinabove as well as modifications and variations whichwould occur to persons skilled in the art upon reading the foregoingdescription and which are not in the prior art.

1. A logic array comprising: an array of logic cells having amultiplicity of inputs and a multiplicity of outputs; wherein each of atleast some of said logic cells comprises at least one look-up table; andcustomized interconnections providing permanent direct interconnectionsamong at least a plurality of said multiplicity of inputs and at least aplurality of said multiplicity of outputs; wherein said customizedinterconnections comprise at least two customized metal layers overlyingsaid logic cells, wherein each of said logic cells also comprises atleast one multiplexer, and wherein at least some of said multiplexersare configured to perform a logic operation by said customizedinterconnections.
 2. A logic array comprising: an array of logic cellshaving a multiplicity of inputs and a multiplicity of outputs; whereineach of at least some of said logic cells comprises at least one look-uptable; and customized interconnections providing permanent directinterconnections among at least a plurality of said multiplicity ofinputs and at least a plurality of said multiplicity of outputs; whereinsaid customized interconnections comprise at least two customized metallayers overlying said logic ceils, wherein said look-up table iscustomized by a custom layer.
 3. A logic array comprising: an array oflogic cells having a multiplicity of inputs and a multiplicity ofoutputs; wherein each of at least some of said logic cells comprises atleast one look-up table; and customized interconnections providingpermanent direct interconnections among at least a plurality of saidmultiplicity of inputs and at least a plurality of said multiplicity ofoutputs; wherein said customized interconnections comprise at least twocustomized metal layers overlying said logic cells, wherein saidcustomized interconnections comprise at least three customized metallayers overlaying said logic cells.
 4. A logic array comprising: anarray of logic cells having a multiplicity of inputs and a multiplicityof outputs; wherein each of at least some of said logic cells comprisesat least one look-up table; and customized interconnections providingpermanent direct interconnections among at least a plurality of saidmultiplicity of inputs and at least a plurality of said multiplicity ofoutputs; wherein said customized interconnections comprise at least twocustomized metal layers overlying said logic cells, wherein saidcustomized metal layers are formed using direct write e-beam technology.5. A semiconductor device comprising: a logic array comprising amultiplicity of logic cells, said logic cells having a multiplicity ofinputs and a multiplicity of outputs, each logic cell including at leastone look-up table and at least one inverter, said inverter having aninverter input and an inverter output, wherein said inverter input andinverter output are part of said multiplicity of inputs and multiplicityof outputs; said logic array also comprising at least one standard metallayer; and metal connection layers overlying said logic array forinterconnecting various ones of said inputs and outputs in a customizedmanner.
 6. A semiconductor device according to claim 5, wherein at leastone of said logic cells also comprises at least one multiplexer, andwherein said multiplexer is configured to perform a logic function bysaid metal connection layers.
 7. A semiconductor device according toclaim 6, wherein said logic function is selected from the group of logicfunctions consisting of: NAND, NOR, AND, OR, and XOR.
 8. A semiconductordevice according to claim 5, wherein said metal connection layerscomprise at least two customized metal layers.
 9. A semiconductor deviceaccording to claim 5, wherein said metal connection layers comprise atleast three customized metal layers.
 10. A semiconductor deviceaccording to claim 5, wherein said standard metal layer comprises atleast one metal strip, and wherein said metal strip has at least twovias overlying it.
 11. A semiconductor device according to claim 5,wherein said look-up table is customized by a custom layer.
 12. Asemiconductor device comprising: a logic array comprising a multiplicityof logic cells, said logic cells having a multiplicity of inputs and amultiplicity of outputs, each logic cell including at least one look-uptable and at least one simple logic gate, said logic gate having atleast one logic gate input and logic gate output, wherein at least someof said logic gate inputs are part of said multiplicity of inputs; saidlogic array also comprising at least one standard metal layer; and metalconnection layers overlying said logic array for interconnecting variousones of said inputs and outputs in a customized manner.
 13. Asemiconductor device according to claim 12, wherein at least one saidlogic cell also comprises an inverter, said inverter having an inverterinput and an inverter output, wherein said inverter input and inverteroutput are part of said at least one input and at least one output. 14.A semiconductor device according to claim 12, wherein said logic gate isa buffer.
 15. A semiconductor device according to claim 12, wherein saidlook-up table is customized by a custom layer.
 16. A semiconductordevice according to claim 12, wherein said standard metal layercomprises at least one metal strip, and wherein said metal strip has atleast two vias overlying it.
 17. A semiconductor device according toclaim 12, wherein said logic cells also comprise at least onemultiplexer, and wherein said multiplexer is configured to perform alogic function by said metal connection layers.
 18. A semiconductordevice according to claim 12, wherein said metal connection layerscomprise at least two customized metal layers.
 19. A semiconductordevice according to claim 12, wherein said metal connection layerscomprise at least three customized metal layers.
 20. A semiconductordevice comprising: a logic array comprising a multiplicity of logiccells, said logic cells having a multiplicity of inputs and amultiplicity of outputs, each logic cell including at least one look-uptable and at least one multiplexer, said logic array also comprising atleast one standard metal layer; and metal connection layers overlyingsaid logic array for interconnecting various inputs and outputs thereofin a customized manner; wherein at least one of said multiplexers isconfigured to perform a two-input logic function by said metalconnection layers, wherein said look-up table is customized by a customvia layer.
 21. A semiconductor device comprising: a logic arraycomprising a multiplicity of logic cells, said logic cells having amultiplicity of inputs and a multiplicity of outputs, each logic cellincluding at least one look-up table and at least one multiplexer, saidlogic array also comprising at least one standard metal layer; and metalconnection layers overlying said logic array for interconnecting variousinputs and outputs thereof in a customized manner; wherein at least oneof said multiplexers is configured to perform a two-input logic functionby said metal connection layers, wherein said standard metal layercomprises at least one metal strip, and wherein said metal strip has atleast two vias overlying it.
 22. A semiconductor device comprising: alogic array comprising a multiplicity of logic cells, said logic cellshaving a multiplicity of inputs and a multiplicity of outputs, eachlogic cell including at least one look-up table and at least onemultiplexer, said logic array also comprising at least one standardmetal layer; and metal connection layers overlying said logic array forinterconnecting various inputs and outputs thereof in a customizedmanner; wherein at least one of said multiplexers is configured toperform a two-input logic function by said metal connection layers,wherein said metal connection layers comprise at least three customizedmetal layers.
 23. A semiconductor device comprising: a logic arraycomprising a multiplicity of logic cells, said logic cells having amultiplicity of inputs and a multiplicity of outputs, each logic cellincluding at least one look-up table, said logic array also comprisingat least one standard metal layer; and metal connection layers overlyingsaid logic array for interconnecting various inputs and outputs thereofin a customized manner; wherein at least one interconnection within saidlogic cell is made by said metal connection layers, wherein saidstandard metal layer comprises at least one metal strip, said metalstrip having at least two vias overlying it.
 24. A semiconductor devicecomprising: a logic array comprising a multiplicity of logic cells, saidlogic cells having a multiplicity of inputs and a multiplicity ofoutputs, each logic cell including at least one look-up table, saidlogic array also comprising at least one standard metal layer; and metalconnection layers overlying said logic array for interconnecting variousinputs and outputs thereof in a customized manner; wherein at least oneinterconnection within said logic cell is made by said metal connectionlayers, wherein said metal connection layers comprise at least onecustom via layer and at least two custom metal layers.
 25. Asemiconductor device comprising: a logic array comprising a multiplicityof logic cells, said logic cells having a multiplicity of inputs and amultiplicity of outputs, each logic cell including at least one look-uptable, said logic array also comprising at least one standard metallayer; and metal connection layers overlying said logic array forinterconnecting various inputs and outputs thereof in a customizedmanner; wherein at least one interconnection within said logic cell ismade by said metal connection layers, wherein said logic array alsocomprises a multiplicity of multiplexers, wherein at least one of saidmultiplexers is configured to perform a logic function by said metalconnection layers.
 26. A semiconductor device comprising: a logic arraycomprising a multiplicity of logic cells, said logic cells having amultiplicity of inputs and a multiplicity of outputs, each logic cellincluding at least one look-up table, said logic array also comprisingat least one standard metal layer; and metal connection layers overlyingsaid logic array for interconnecting various inputs and outputs thereofin a customized manner; wherein at least one interconnection within saidlogic cell is made by said metal connection layers, wherein said logicfunction is selected from the group of logic functions consisting of:NAND, NOR, AND, OR, and XOR.
 27. A semiconductor device comprising: alogic array comprising a multiplicity of logic cells, said logic cellshaving a multiplicity of inputs and a multiplicity of outputs, eachlogic cell including at least one look-up table, said logic array alsocomprising at least one standard metal layer; and metal connectionlayers overlying said logic array for interconnecting various inputs andoutputs thereof in a customized manner; wherein at least oneinterconnection within said logic cell is made by said metal connectionlayers, wherein said logic cells includes at least one simple logic gateselectably connected to at least one of said multiplicity of inputs orat least one of said multiplicity of outputs.
 28. A semiconductor devicecomprising: a logic array comprising a multiplicity of logic cells, saidlogic cells having a multiplicity of inputs and a multiplicity ofoutputs, each logic cell including at least one look-up table, saidlogic array also comprising at least one standard metal layer; and metalconnection layers overlying said logic array for interconnecting variousinputs and outputs thereof in a customized manner; wherein at least oneinterconnection within said logic cell is made by said metal connectionlayers, wherein said logic array comprises at least one simple logicgate, said logic gate having a logic gate input, and wherein said metalconnection layers also interconnect said logic gate input with one ormore of said outputs in a customized manner.
 29. A semiconductor devicecomprising: a logic array comprising a multiplicity of logic cells, saidlogic cells having a multiplicity of inputs and a multiplicity ofoutputs; each logic cell including at least two look-up tables and atleast one flip-flop; said logic array also comprising metal connectionlayers overlying said logic array for interconnecting various ones ofsaid inputs and outputs in a customized manner.
 30. A semiconductordevice according to claim 29, wherein said metal connection layerscomprise at least three customized metal layers.
 31. A semiconductordevice according to claim 30, wherein said logic array comprises atleast two standard metal layers.
 32. A semiconductor device according toclaim 29, wherein said look-up table is customized by a custom vialayer.
 33. A semiconductor device comprising: a logic array comprising amultiplicity of logic cells, said logic cells having a multiplicity ofinputs and a multiplicity of outputs, each logic cell including at leastone look-up table, said logic array also comprising at least one simplelogic gate and one standard metal layer; said logic gate having at leastone logic gate input and logic gate output, and metal connection layersoverlying said logic array for interconnecting various ones of saidinputs and outputs and said logic gate input; in a customized manner.34. A semiconductor device according to claim 33, wherein at least onesaid logic cell also comprises an inverter, said inverter having aninverter input and an inverter output, wherein said inverter input orinverter output is part of said multiplicity of inputs and multiplicityof outputs.
 35. A semiconductor device according to claim 33, whereinsaid logic gate is a buffer.
 36. A semiconductor device according toclaim 33, wherein said look-up table is customized by a custom layer.37. A semiconductor device according to claim 33, wherein said standardmetal layer comprises at least one metal strip, and wherein said metalstrip has at least two vias overlying it.
 38. A semiconductor deviceaccording to claim 33, wherein at least one of said logic cells alsocomprises at least one multiplexer, and wherein said multiplexer isconfigured to perform a logic function by said metal connection layers.39. A semiconductor device according to claim 33, wherein said metalconnection layers comprise at least two customized metal layers.
 40. Asemiconductor device according to claim 33, wherein said metalconnection layers comprise at least three customized metal layers.
 41. Asemiconductor device according to claim 33, wherein said logic gate isan inverter.
 42. A semiconductor device according to claim 33, whereinsaid logic gate is a NAND.
 43. A semiconductor device according to claim33, wherein said logic gate is a NOR.
 44. A semiconductor deviceaccording to claim 29, wherein at least one said logic cell includes atleast one inverter.
 45. A semiconductor device comprising: a logic arraycomprising a multiplicity of logic cells, said logic cells having amultiplicity of inputs and a multiplicity of outputs, each logic cellincluding at least one look-up table, said logic array also comprisingat least one standard metal layer; and metal connection layers overlyingsaid logic array for interconnecting various inputs and outputs thereofin a customized manner; wherein at least one interconnection within saidlogic cell is made by said metal connection layers, wherein amultiplicity of said interconnections within said logic cell is made bysaid metal connection layers.
 46. A semiconductor device comprising: alogic array comprising a multiplicity of logic cells, said logic cellshaving a multiplicity of inputs and a multiplicity of outputs, eachlogic cell including at least one look-up table, said logic array alsocomprising at least one standard metal layer; and metal connectionlayers overlying said logic array for interconnecting various inputs andoutputs thereof in a customized manner; wherein at least oneinterconnection within said logic cell is made by said metal connectionlayers, wherein at least one of said logic cells includes at least twolook-up tables, and wherein at least one of said interconnections withinsaid logic cell is between an output of a first of said look-up tablesand an input of a second of said look-up tables.
 47. A semiconductordevice comprising: a logic array comprising a multiplicity of logiccells, said logic cells having a multiplicity of inputs and amultiplicity of outputs, each logic cell including at least one look-uptable, said logic array also comprising at least one standard metallayer; and metal connection layers overlying said logic array forinterconnecting various inputs and outputs thereof in a customizedmanner; wherein at least one interconnection within said logic cell ismade by said metal connection layers, wherein at least one of said logiccells includes at least one look-up table and at least one inverter; andwherein at least one of said interconnections within said logic cell isbetween an output of one of said look-up tables and an input of one ofsaid inverters.